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  • Journal article
    Cho Y, He T, Moss B, Benetti D, Liang C, Tian L, Hart LJF, Wilson AA, Taniguchi Y, Cui J, Yang M, Eslava S, Yamaguchi A, Miyauchi M, Durrant JRet al., 2024,

    Analyzing the temperature dependence of titania photocatalysis: kinetic competition between water oxidation catalysis and back electron–hole recombination

    , ACS Catalysis, Vol: 14, Pages: 16543-16550, ISSN: 2155-5435

    This study examines the kinetic origins of the temperature dependence of photoelectrochemical water oxidation on nanostructured titania photoanodes. We observe that the photocurrent is enhanced at 50 °C relative to 20 °C, with this enhancement being most pronounced (by up to 70%) at low anodic potentials (<+0.6 V vs RHE). Over this low potential range, the photocurrent magnitude is largely determined by kinetic competition between water oxidation catalysis (WOC) and recombination between surface holes and bulk electrons (back electron–hole recombination, BER). We quantify the BER process by transient photocurrent analyses under pulsed irradiation. Remarkably, we find that the kinetics of BER (∼90 ms half-time) are independent of temperature. In contrast, the kinetics of WOC, determined from the analysis of the photoinduced absorption of accumulated surface holes, are found to accelerate up to 2-fold at 50 °C relative to 20 °C. We conclude that the enhanced photocurrent densities observed in the low-applied potential region result primarily from the accelerated WOC, reducing losses due to the competing BER pathway. At higher applied potentials (>+0.6 V vs RHE), a smaller (∼10%) enhancement in photocurrent density is observed at 50 °C relative to 20 °C. Photoinduced absorption studies, correlated with studies using triethanolamine as a hole scavenger, indicate that this more modest enhancement at anodic potentials primarily results from an enhanced charge separation efficiency. We conclude by discussing the implications of these results for the practical application of photoanodic WOC under solar irradiation, influenced by these temperature-independent and -dependent underlying kinetic processes.
  • Journal article
    Yang M, Oldham L, Daboczi M, Baghdadi Y, Cui J, Benetti D, Zhang W, Durrant JR, Hankin A, Eslava Set al., 2024,

    Advancing hematite photoanodes for photoelectrochemical water splitting: the impact of g-C3N4 supported Ni-CoP on photogenerated hole dynamics

    , Advanced Energy Materials, Vol: 14, ISSN: 1614-6832

    The increasing demand for clean hydrogen necessitates the rapid development of efficient photoanodes to catalyze the water oxidation half-reaction effectively. Here a strategy is introduced to fabricate photoanodes that synergistically combine and leverage the properties of porous Ti-doped hematite (Ti-Fe2O3) and graphitic carbon nitride (g-C3N4) nanosheets anchored with in situ grown Ni-doped CoP co-catalyst (Ni-CoP). The resulting hybrid photoanodes exhibit >7 times higher photocurrent density at +1.23 VRHE compared with Ti-Fe2O3 photoanodes. Comprehensive characterization techniques, including ambient photoemission spectroscopy, intensity-modulated photocurrent spectroscopy, and transient absorption spectroscopy complementarily reveal the key impact of g-C3N4 in these composites with enhanced solar oxygen evolution reaction: The incorporation of g-C3N4 leads to enhanced charge separation through a type-II heterojunction, thereby increasing the hole flux at the surface, and extending the charge carrier lifetime to the ms-s range needed for water oxidation. Additionally, g-C3N4 facilitates efficient transfer of photogenerated holes to the fine Ni-CoP nanoparticles confined in the graphitic matrix for a boosted oxygen evolution reaction. These findings highlight the advantages of complex heterostructure photoanodes and demonstrate a new application of g-C3N4 as a multifunctional support of co-catalysts for future photoanodes with enhanced performance.
  • Journal article
    Baghdadi Y, Daboczi M, Temerov F, Yang M, Cui J, Eslava Set al., 2024,

    A g-C3N4/rGO/Cs3Bi2Br9 mediated Z-schemeheterojunction for enhanced photocatalytic CO2reduction

    , Journal of Materials Chemistry A, Vol: 12, Pages: 16383-16395, ISSN: 2050-7488

    Photocatalytic CO2 reduction plays a crucial role in advancing solar fuels, and enhancing the efficiency of the chosen photocatalysts is essential for sustainable energy production. This study demonstrates advancements in the performance of g-C3N4 as a photocatalyst achieved through surface modifications such as exfoliation to increase surface area and surface oxidation for improved charge separation. We also introduce reduced graphene oxide (rGO) in various ratios to both bulk and exfoliated g-C3N4, which effectively mitigates charge recombination and establishes an optimal ratio for enhanced efficiency. g-C3N4/rGO serves to fabricate a hybrid organic/inorganic heterojunction with Cs3Bi2Br9, resulting in a g-C3N4/rGO/Cs3Bi2Br9 composite. This leads to a remarkable increase in photocatalytic conversion of CO2 and H2O to CO, H2 and CH4 at rates of 54.3 (±2.0) μmole− g−1 h−1, surpassing that of pure Cs3Bi2Br9 (11.2 ± 0.4 μmole− g−1 h−1) and bulk g-C3N4 (5.5 ± 0.5 μmole− g−1 h−1). The experimentally determined energy diagram indicates that rGO acts as a solid redox mediator between g-C3N4 and Cs3Bi2Br9 in a Z-scheme heterojunction configuration, ensuring that the semiconductor (Cs3Bi2Br9) with the shallowest conduction band drives the reduction and the one with the deepest valence band (g-C3N4) drives the oxidation. The successful formation of this high-performance heterojunction underscores the potential of the developed composite as a photocatalyst for CO2 reduction, offering promising prospects for advancing the field of solar fuels and achieving sustainable energy goals.
  • Journal article
    Lewis BF, Huang C, Itskou I, Mallia G, Harrison NM, Southouse J, Eslava Set al., 2024,

    Ca-Doped PrFeO<inf>3</inf> Photocathodes with Enhanced Photoelectrochemical Activity

    , Solar RRL, Vol: 8

    Perovskite oxides, renowned for their adaptable structure and optoelectronic characteristics, hold significant potential for applications in catalysis and photoelectrochemical (PEC) processes. In this research, the preparation of praseodymium iron oxide (PrFeO3) by spin coating and the impact of incorporating a calcium (Ca) dopant on its PEC efficacy as photocathodes are investigated. Spin coating of a polymer containing sol–gel yields thin films with uniform morphology and porosity, facilitating effective semiconductor/electrolyte interactions, as characterized by scanning electron microscopy analyses. Evaluation of transient photocurrent responses reveals that introducing Ca at a 5 at% doping level significantly enhances the PEC activity of PrFeO3, resulting in an optimal photocurrent of −124 μA cm−2 at +0.43 V vs. a reversible hydrogen electrode (VRHE) under simulated sunlight conditions. This enhancement is accompanied by an incident photon-to-current efficiency (IPCE) of 3.8% at +0.43 VRHE and 350 nm, along with an onset potential of +1.1 VRHE. Ultraviolet and visible spectroscopy analyses indicate an increase in light-absorption capabilities in the Ca-doped films and a noticeable reduction in bandgap compared to the undoped counterparts, further supported by IPCE measurements. In the findings, the significant role of dopants in augmenting the photocurrent performance of stable perovskite oxides, highlighting their potential in advancing photon conversion technologies, is underscored.
  • Journal article
    Temerov F, Greco R, Celis J, Eslava S, Wang W, Yamamoto T, Cao Wet al., 2024,

    Activating 2D MoS<inf>2</inf> by loading 2D Cu–S nanoplatelets for improved visible light photocatalytic hydrogen evolution, drug degradation, and CO<inf>2</inf> reduction

    , Results in Materials, Vol: 22

    Finding reliable photocatalysts capable of driving reactions using only sunlight is more needed than ever. A variety of strategies to harvest sunlight and convert it into chemical energy have been successfully utilized such as synthesizing nanostructures, using metal nanoparticles, doping, and others. In this work, we discover a facile way to anchor CuS nanoplatelets on 2D MoS2 by the solvothermal method using ethylene glycol (EG) as both a reduction agent and an exfoliating agent of bulk MoS2. Using CuS as a co-catalysis on MoS2 with their huge surface areas, led to improved photocatalytic activity for three different applications including H2 evolution, CO2 reduction, and endosulfan degradation. Specifically, Cu–S@MoS2 3% nanocomposite produced 9.86 μmol g−1 h−1 of H2, 0.48 μmol g−1 h−1 of CO and full decomposition of endosulfan within 6 h. The Cu-loaded MoS2 nanocomposites were thoroughly characterized by spectroscopic (including synchrotron-based spectroscopy) and microscopic methods to understand the formation of Cu–S during the solvothermal process. Moreover, the role of the EG during the synthetic procedure was revealed experimentally and studied theoretically via DFT simulations.
  • Journal article
    Stewart K, Pagano K, Tan E, Daboczi M, Rimmele M, Luke J, Eslava S, Kim J-Set al., 2024,

    Understanding effects of alkyl side-chain density on polaron formation via electrochemical doping in thiophene polymers

    , Advanced Materials, Vol: 36, ISSN: 0935-9648

    Polarons exist when charges are injected into organic semiconductors due to their strong coupling with the lattice phonons, significantly affecting electronic charge-transport properties. Understanding the formation and (de)localization of polarons is therefore critical for further developing organic semiconductors as a future electronics platform. However, there are very few studies reported in this area. In particular, there is no direct in situ monitoring of polaron formation and identification of its dependence on molecular structure and impact on electrical properties, limiting further advancement in organic electronics. Herein, how a minor modification of side-chain density in thiophene-based conjugated polymers affects the polaron formation via electrochemical doping, changing the polymers’ electrical response to the surrounding dielectric environment for gas sensing, is demonstrated. It is found that the reduction in side-chain density results in a multistep polaron formation, leading to an initial formation of localized polarons in thiophene units without side chains. Reduced side-chain density also allows the formation of a high density of polarons with fewer polymer structural changes. More numerous but more localized polarons generate a stronger analyte response but without the selectivity between polar and non-polar solvents, which is different from the more delocalized polarons that show clear selectivity. The results provide important molecular understanding and design rules for the polaron formation and its impact on electrical properties.
  • Journal article
    Wu D-T, Zhu W-X, Dong Y, Daboczi M, Ham G, Hsieh H-J, Huang C-J, Xu W, Henderson C, Kim J-S, Eslava S, Cha H, Macdonald TJ, Lin C-Tet al., 2024,

    Enhancing the efficiency and stability of tin-lead perovskite solar cells via sodium hydroxide dedoping of PEDOT:PSS

    , small methods, ISSN: 2366-9608

    Tin-lead (Sn-Pb) perovskite solar cells (PSCs) have gained interest as candidates for the bottom cell of all-perovskite tandem solar cells due to their broad absorption of the solar spectrum. A notable challenge arises from the prevalent use of the hole transport layer, PEDOT:PSS, known for its inherently high doping level. This high doping level can lead to interfacial recombination, imposing a significant limitation on efficiency. Herein, NaOH is used to dedope PEDOT:PSS, with the aim of enhancing the efficiency of Sn-Pb PSCs. Secondary ion mass spectrometer profiles indicate that sodium ions diffuse into the perovskite layer, improving its crystallinity and enlarging its grains. Comprehensive evaluations, including photoluminescence and nanosecond transient absorption spectroscopy, confirm that dedoping significantly reduces interfacial recombination, resulting in an open-circuit voltage as high as 0.90 V. Additionally, dedoping PEDOT:PSS leads to increased shunt resistance and high fill factor up to 0.81. As a result of these improvements, the power conversion efficiency is enhanced from 19.7% to 22.6%. Utilizing NaOH to dedope PEDOT:PSS also transitions its nature from acidic to basic, enhancing stability and exhibiting less than a 7% power conversion efficiency loss after 1176 h of storage in N2 atmosphere.
  • Journal article
    Zhu Z, Daboczi M, Chen M, Xuan Y, Liu X, Eslava Set al., 2024,

    Ultrastable halide perovskite CsPbBr3 photoanodes achieved with electrocatalytic glassy-carbon and boron-doped diamond sheets

    , Nature Communications, Vol: 15, ISSN: 2041-1723

    Halide perovskites exhibit exceptional optoelectronic properties for photoelectrochemical production of solar fuels and chemicals but their instability in aqueous electrolytes hampers their application. Here we present ultrastable perovskite CsPbBr3-based photoanodes achieved with both multifunctional glassy carbon and boron-doped diamond sheets coated with Ni nanopyramids and NiFeOOH. These perovskite photoanodes achieve record operational stability in aqueous electrolytes, preserving 95% of their initial photocurrent density for 168 h of continuous operation with the glassy carbon sheets and 97% for 210 h with the boron-doped diamond sheets, due to the excellent mechanical and chemical stability of glassy carbon, boron-doped diamond, and nickel metal. Moreover, these photoanodes reach a low water-oxidation onset potential close to +0.4 VRHE and photocurrent densities close to 8 mA cm-2 at 1.23 VRHE, owing to the high conductivity of glassy carbon and boron-doped diamond and the catalytic activity of NiFeOOH. The applied catalytic, protective sheets employ only earth-abundant elements and straightforward fabrication methods, engineering a solution for the success of halide perovskites in stable photoelectrochemical cells.
  • Journal article
    Liu S-C, Lin H-Y, Hsu S-E, Wu D-T, Sathasivam S, Daboczi M, Hsieh H-J, Zeng C-S, Hsu T-G, Eslava S, Macdonald TJ, Lin C-Tet al., 2024,

    Highly reproducible self-assembled monolayer based perovskite solar cells <i>via</i> amphiphilic polyelectrolyte

    , JOURNAL OF MATERIALS CHEMISTRY A, Vol: 12, Pages: 2856-2866, ISSN: 2050-7488
  • Journal article
    Fernandez-Catala J, Jussila L, Daboczi M, Temerov F, Eslava S, Greco R, Cao Wet al., 2023,

    Shape-Controlled Synthesis of Cu<sub>3</sub>TeO<sub>6</sub> Nanoparticles with Photocatalytic Features

    , CRYSTAL GROWTH & DESIGN, Vol: 23, Pages: 8828-8837, ISSN: 1528-7483
  • Journal article
    Daboczi M, Cui J, Temerov F, Eslava Set al., 2023,

    Scalable All-Inorganic Halide Perovskite Photoanodes with >100 h Operational Stability Containing Earth-Abundant Materials

    , ADVANCED MATERIALS, Vol: 35, ISSN: 0935-9648
  • Journal article
    Baghdadi Y, Temerov F, Cui J, Daboczi M, Rattner E, Sena MS, Itskou I, Eslava Set al., 2023,

    Cs3Bi2Br9/g‑C3N4 direct Z‑scheme heterojunction for enhancedphotocatalytic reduction of CO2 to CO

    , Chemistry of Materials, Vol: 35, Pages: 8607-8620, ISSN: 0897-4756

    Lead-free halide perovskite derivative Cs3Bi2Br9 has recently been found to possess optoelectronic properties suitable for photocatalytic CO2 reduction reactions to CO. However, further work needs to be performed to boost charge separation for improving the overall efficiency of the photocatalyst. This report demonstrates the synthesis of a hybrid inorganic/organic heterojunction between Cs3Bi2Br9 and g-C3N4 at different ratios, achieved by growing Cs3Bi2Br9 crystals on the surface of g-C3N4 using a straightforward antisolvent crystallization method. The synthesized powders showed enhanced gas-phase photocatalytic CO2 reduction in the absence of hole scavengers of 14.22 (±1.24) μmol CO g–1 h–1 with 40 wt % Cs3Bi2Br9 compared with 1.89 (±0.72) and 5.58 (±0.14) μmol CO g–1 h–1 for pure g-C3N4 and Cs3Bi2Br9, respectively. Photoelectrochemical measurements also showed enhanced photocurrent in the 40 wt % Cs3Bi2Br9 composite, demonstrating enhanced charge separation. In addition, stability tests demonstrated structural stability upon the formation of a heterojunction, even after 15 h of illumination. Band structure alignment and selective metal deposition studies indicated the formation of a direct Z-scheme heterojunction between the two semiconductors, which boosted charge separation. These findings support the potential of hybrid organic/inorganic g-C3N4/Cs3Bi2Br9 Z-scheme photocatalyst for enhanced CO2 photocatalytic activity and improved stability.
  • Journal article
    Sena MS, Cui J, Baghdadi Y, Rattner E, Daboczi M, Lopes-Moriyama AL, dos Santos AG, Eslava Set al., 2023,

    Lead-free halide perovskite Cs2AgBiBr6/bismuthene composites for improved CH4 production in photocatalytic CO2 reduction

    , ACS Applied Energy Materials, Vol: 6, Pages: 10193-10204, ISSN: 2574-0962

    CO2 photocatalytic conversion into value-added fuels through solar energy is a promising way of storing renewable energy while simultaneously reducing the concentration of CO2 in the atmosphere. Lead-based halide perovskites have recently shown great potential in various applications such as solar cells, optoelectronics, and photocatalysis. Even though they show high performance, the high toxicity of Pb2+ along with poor stability under ambient conditions restrains the application of these materials in photocatalysis. In this respect, we developed an in situ assembly strategy to fabricate the lead-free double perovskite Cs2AgBiBr6 on a 2D bismuthene nanosheet prepared by a ligand-assisted reprecipitation method for a liquid-phase CO2 photocatalytic reduction reaction. The composite improved the production and selectivity of the eight-electron CH4 pathway compared with the two-electron CO pathway, storing more of the light energy harvested by the photocatalyst. The Cs2AgBiBr6/bismuthene composite shows a photocatalytic activity of 1.49(±0.16) μmol g–1 h–1 CH4, 0.67(±0.14) μmol g–1 h–1 CO, and 0.75(±0.20) μmol g–1 h–1 H2, with a CH4 selectivity of 81(±1)% on an electron basis with 1 sun. The improved performance is attributed to the enhanced charge separation and suppressed electron–hole recombination due to good interfacial contact between the perovskite and bismuthene promoted by the synthesis method.
  • Journal article
    Cui J, Daboczi M, Cui Z, Gong M, Flitcroft J, Skelton J, Parker SC, Eslava Set al., 2024,

    BiVO<sub>4</sub> Photoanodes Enhanced with Metal Phosphide Co-Catalysts: Relevant Properties to Boost Photoanode Performance

    , SMALL, ISSN: 1613-6810
  • Journal article
    Yang M, Cui J, Daboczi M, Law RV, Luke J, Kim J-S, Hankin A, Eslava Set al., 2023,

    Interplay between Collective and Localized Effects of Point Defects on Photoelectrochemical Performance of TiO<sub>2</sub> Photoanodes for Oxygen Evolution

    , ADVANCED MATERIALS INTERFACES, ISSN: 2196-7350
  • Journal article
    Greco R, Baxauli-Marin L, Temerov F, Daboczi M, Eslava S, Niu Y, Zakharov A, Zhang M, Li T, Cao Wet al., 2023,

    Activation of 2D cobalt hydroxide with 0D cobalt oxide decoration for microplastics degradation and hydrogen evolution

    , CHEMICAL ENGINEERING JOURNAL, Vol: 471, ISSN: 1385-8947
  • Journal article
    Moruzzi F, Zhang W, Purushothaman B, Gonzalez-Carrero S, Aitchison CM, Willner B, Ceugniet F, Lin Y, Kosco J, Chen H, Tian J, Alsufyani M, Gibson JS, Rattner E, Baghdadi Y, Eslava S, Neophytou M, Durrant JR, Steier L, McCulloch Iet al., 2023,

    Solution-processable polymers of intrinsic microporosity for gas-phase carbon dioxide photoreduction

    , Nature Communications, Vol: 14, ISSN: 2041-1723

    Four solution-processable, linear conjugated polymers of intrinsic porosity are synthesised and tested for gas phase carbon dioxide photoreduction. The polymers’ photoreduction efficiency is investigated as a function of their porosity, optical properties, energy levels and photoluminescence. All polymers successfully form carbon monoxide as the main product, without the addition of metal co-catalysts. The best performing single component polymer yields a rate of 66 μmol h−1 m−2, which we attribute to the polymer exhibiting macroporosity and the longest exciton lifetimes. The addition of copper iodide, as a source of a copper co-catalyst in the polymers shows an increase in rate, with the best performing polymer achieving a rate of 175 μmol h−1 m−2. The polymers are active for over 100 h under operating conditions. This work shows the potential of processable polymers of intrinsic porosity for use in the gas phase photoreduction of carbon dioxide towards solar fuels.
  • Journal article
    Temerov F, Baghdadi Y, Rattner E, Eslava Set al., 2022,

    A review on halide perovskite-based photocatalysts: key factors and challenges

    , ACS Applied Energy Materials, Vol: 5, Pages: 14605-14637, ISSN: 2574-0962

    A growing number of research articles have been published on the use of halide perovskite materials for photocatalytic reactions. These articles extend these materials’ great success from solar cells to photocatalytic technologies such as hydrogen production, CO2 reduction, dye degradation, and organic synthesis. In the present review article, we first describe the background theory of photocatalysis, followed by a description on the properties of halide perovskites and their development for photocatalysis. We highlight key intrinsic factors influencing their photocatalytic performance, such as stability, electronic band structure, and sorption properties. We also discuss and shed light on key considerations and challenges for their development in photocatalysis, such as those related to reaction conditions, reactor design, presence of degradable organic species, and characterization, especially for CO2 photocatalytic reduction. This review on halide perovskite photocatalysts will provide a better understanding for their rational design and development and contribute to their scientific and technological adoption in the wide field of photocatalytic solar devices.
  • Journal article
    Cui J, Daboczi M, Regue M, Chin Y, Pagano K, Zhang J, Isaacs MA, Kerherve G, Mornto A, West J, Gimenez S, Kim J, Eslava Set al., 2022,

    2D bismuthene as a functional interlayer between BiVO4 and NiFeOOH for enhanced oxygen-evolution photoanodes

    , Advanced Functional Materials, Vol: 32, Pages: 1-12, ISSN: 1616-301X

    BiVO4 has attracted wide attention for oxygen-evolution photoanodes in water-splitting photoelectrochemical devices. However, its performance is hampered by electron-hole recombination at surface states. Herein, partially oxidized two-dimensional (2D) bismuthene is developed as an effective, stable, functional interlayer between BiVO4 and the archetypal NiFeOOH co-catalyst. Comprehensive (photo)electrochemical and surface photovoltage characterizations show that NiFeOOH can effectively increase the lifetime of photogenerated holes by passivating hole trap states of BiVO4; however, it is limited in influencing electron trap states related to oxygen vacancies (VO). Loading bismuthene on BiVO4 photoanodes increases the density of VO that are beneficial for the oxygen evolution reaction via the formation of oxy/hydroxyl-based water oxidation intermediates at the surface. Moreover, bismuthene increases interfacial band bending and fills the VO-related electron traps, leading to more efficient charge extraction. With the synergistic interaction of bismuthene and NiFeOOH on BiVO4, this composite photoanode achieves a 5.8-fold increase in photocurrent compared to bare BiVO4 reaching a stable 3.4 (±0.2) mA cm–2 at a low bias of +0.8 VRHE or 4.7(±0.2) mA cm–2 at +1.23 VRHE. The use of 2D bismuthene as functional interlayer provides a new strategy to enhance the performance of photoanodes.
  • Journal article
    Eslava S, Hintermair U, 2021,

    Editorial: Recent advances in water splitting

    , CURRENT OPINION IN GREEN AND SUSTAINABLE CHEMISTRY, Vol: 32, ISSN: 2452-2236
  • Journal article
    Kumar S, Eslava S, 2021,

    Mechanochemically synthesized Pb-free halide perovskite-based Cs2AgBiBr6-Cu-RGO nanocomposite for photocatalytic CO2 reduction

    , Journal of Materials Chemistry A, Vol: 5/5/21, Pages: 12179-12187, ISSN: 2050-7488

    Pb-based halide perovskites have recently showed great potential in various applications such as solar cells, optoelectronics and photocatalysis. Despite their high performance, the Pb2+ toxicity along with poor stability hinders long term applications in photocatalysis. Herein, we report mechanochemically prepared Pb-free Cs2AgBiBr6 double perovskite nanoplates and their heterostructure with Cu-loaded reduced graphene oxide (Cu–RGO) for gas-phase photocatalytic CO2 reduction using water vapor as the proton source in the absence of a hole scavenger. The resulting Cs2AgBiBr6–Cu–RGO nanocomposite shows significant photocatalytic activity of 10.7 (±0.6) μmol CH4 g−1 h−1, 1.9 (±0.3) μmol CO g−1 h−1 and 1.0 (±0.2) μmol H2 g−1 h−1, with a CH4 selectivity of 93.0 (±0.5)% on an electron basis with 1 sun and a remarkable apparent quantum efficiency of 0.89 (±0.21)% at 590 nm. A further 32% enhancement in photocatalytic activity on an electron basis is achieved when the light intensity is doubled (2 suns). The high performance was attributed to their improved charge separation and suppressed electron–hole recombination, along with extended visible light absorption, better stability in a humid environment and improved CO2 adsorption. These findings support Cs2AgBiBr6 as a potential Pb-free alternative to conventional halide perovskites for photocatalytic solar-to-fuel conversion and CO2 utilization.
  • Journal article
    Schukraft GEM, Woodward RT, Kumar S, Sachs M, Eslava S, Petit Cet al., 2021,

    Hypercrosslinked polymers as a photocatalytic platform for visible-light-driven CO2 photoreduction using H2O

    , ChemSusChem: chemistry and sustainability, energy and materials, Vol: 14, Pages: 1720-1727, ISSN: 1864-5631

    The design of robust, high‐performance photocatalysts is key for the success of solar fuel production by CO2 conversion. In this study, hypercrosslinked polymer (HCP) photocatalysts have been developed for the selective reduction of CO2 to CO, combining excellent CO2 sorption capacities, good general stabilities, and low production costs. HCPs are active photocatalysts in the visible light range, significantly outperforming the benchmark material, TiO2 P25, using only sacrificial H2O. It is hypothesized that superior H2O adsorption capacities facilitate access to photoactive sites, improving photocatalytic conversion rates when compared to sacrificial H2. These polymers are an intriguing set of organic photocatalysts, displaying no long‐range order or extended π‐conjugation. The as‐synthesized networks are the sole photocatalytic component, requiring no added cocatalyst doping or photosensitizer, representing a highly versatile and exciting platform for solar‐energy conversion.
  • Journal article
    Zhang J, Cui J, Eslava S, 2021,

    Oxygen evolution catalysts at transition metal oxide photoanodes: their differing roles for solar water splitting

    , Advanced Energy Materials, Vol: 11, Pages: 1-27, ISSN: 1614-6832

    In the field of photoelectrochemical water splitting for hydrogen production, dedicated efforts have recently been made to improve water oxidation at photoanodes, and in particular, to accelerate the poor kinetics of the oxygen evolution reaction which is a key step in achieving a viable photocurrent density for industrialization. To this end, coating the photoanode semiconductors with oxygen evolution catalysts (OECs) has been one of the most popular options. The roles of OECs have been found to be multifold, as opposed to exclusively catalytic. This review aims to unravel the complexity of the interfacial processes arising from the material properties of both semiconductors and OECs, and to rationalize the variation in findings in the literature regarding the roles of OECs. Light is also shed on some of the most useful characterization techniques that probe the dynamics of photogenerated holes, to answer some of the field's most challenging mechanistic questions. Finally, some ideas and suggestions on the design principles of OECs are proposed.
  • Journal article
    Rood SC, Pastor-Algaba O, Tosca-Princep A, Pinho B, Isaacs M, Torrente-Murciano L, Eslava Set al., 2021,

    Synergistic effect of simultaneous doping of ceria nanorods with Cu and Cr on CO oxidation and NO reduction

    , Chemistry: A European Journal, Vol: 27, Pages: 2165-2174, ISSN: 0947-6539

    Ceria particles play a key role in catalytic applications such as automotive three-way catalytic systems in which toxic CO and NO are oxidized and reduced to safe CO2 and N2, respectively. In this work, we explore the incorporation of Cu and Cr metals as dopants in the crystal structure of ceria nanorods prepared by a single-step hydrothermal synthesis. XRD, Raman and XPS confirm the incorporation of Cu and Cr in the ceria crystal lattices, offering ceria nanorods with a higher concentration of oxygen vacancies. XPS also confirms the presence of Cr and Cu surface species. H2-TPR and XPS analysis show that the simultaneous Cu and Cr co-doping results in a catalyst with a higher surface Cu concentration and a much-enhanced surface reducibility, in comparison with either undoped or singly doped (Cu or Cr) ceria nanorods. While single Cu doping enhances catalytic CO oxidation and Cr doping improves catalytic NO reduction, co-doping with both Cu and Cr enhances the benefits of both dopants in a synergistic manner employing roughly a quarter of dopant weight.
  • Journal article
    Hammond OS, Atri RS, Bowron DT, de Campo L, Diaz-Moreno S, Keenan LL, Doutch J, Eslava S, Edler KJet al., 2021,

    Structural evolution of iron forming iron oxide in a deep eutectic-solvothermal reaction

    , NANOSCALE, Vol: 13, Pages: 1723-1737, ISSN: 2040-3364
  • Journal article
    Regue M, Ahmet IY, Bassi PS, Johnson AL, Fiechter S, van de Krol R, Abdi FF, Eslava Set al., 2020,

    Zn-Doped Fe<sub>2</sub>TiO<sub>5</sub> Pseudobrookite-Based Photoanodes Grown by Aerosol-Assisted Chemical Vapor Deposition

    , ACS APPLIED ENERGY MATERIALS, Vol: 3, Pages: 12066-12077, ISSN: 2574-0962
  • Journal article
    Kumar N, Kumar S, Gusain R, Manyala N, Eslava S, Ray SSet al., 2020,

    Polypyrrole-Promoted rGO-MoS<sub>2</sub> Nanocomposites for Enhanced Photocatalytic Conversion of CO<sub>2</sub> and H<sub>2</sub>O to CO, CH<sub>4</sub>, and H<sub>2</sub> Products

    , ACS APPLIED ENERGY MATERIALS, Vol: 3, Pages: 9897-9909, ISSN: 2574-0962
  • Journal article
    Temerov F, Pham K, Juuti P, Makela JM, Grachova E, Kumar S, Eslava S, Saarinen JJet al., 2020,

    Silver-Decorated TiO<sub>2</sub> Inverse Opal Structure for Visible Light-Induced Photocatalytic Degradation of Organic Pollutants and Hydrogen Evolution

    , ACS APPLIED MATERIALS & INTERFACES, Vol: 12, Pages: 41200-41210, ISSN: 1944-8244
  • Book chapter
    Regue Grino M, Kumar S, Eslava S, 2020,

    Recent Advances in Photocatalytic Materials for Solar Fuel Production from Water and Carbon Dioxide

    , Heterogeneous Catalysis for Energy Applications, ISBN: 978-1-78801-718-3

    In recent years, photocatalysis has received significant attention because of its clean way of converting water or carbon dioxide into sustainable chemical fuels, providing promising and viable routes to overcome both renewable energy demand and global climate change. This chapter focuses on recent progress in the design and synthesis of sustainable photocatalytic materials, namely novel metal oxides, perovskites, metal–organic frameworks, metal sulfides, layered double hydroxides and plasmonic and metal-free materials. Advances in the preparation of these photocatalysts are reviewed, revealing efficient strategies to enhance their photocatalytic activity to produce hydrogen and carbon-based fuels such as carbon monoxide and methane from inexhaustible water and carbon dioxide. Emphasis is given to the strategies that maximize the visible light absorption of the solar spectrum and charge separation and transfer; for example, through forming heterojunctions of nanostructured materials. This chapter also highlights various strategies adopted for improving not only the photoconversion efficiency, but also the selectivity of certain carbon-based fuels. Adopting these advances within the scientific community will ensure more rapid progress towards high solar to fuel conversions and future commercialization of photocatalytic devices.
  • Journal article
    Schukraft GM, Woodward R, Kumar S, Sachs M, Eslava S, Petit Cet al., 2020,

    Hypercrosslinked Polymers as a Photocatalytic Platform for Visible-Light-Driven CO2 Photoreduction Using H2O

    <jats:p>The design of robust, high-performance photocatalysts is key for the success of solar fuel production <jats:italic>via</jats:italic> CO<jats:sub>2</jats:sub>conversion. Herein, we present hypercrosslinked polymer (HCP) photocatalysts for the selective reduction of CO<jats:sub>2</jats:sub> to CO, combining excellent CO<jats:sub>2</jats:sub> sorption capacities, good general stabilities, and low production costs. HCPs are active photocatalysts in the visible light range, significantly out-performing the benchmark material, TiO<jats:sub>2</jats:sub> P25, using only sacrificial H<jats:sub>2</jats:sub>O. We hypothesise that superior H<jats:sub>2</jats:sub>O adsorption capacities led to concentration at photoactive sites, improving photocatalytic conversion rates when compared to sacrificial H<jats:sub>2</jats:sub>. These polymers are an intriguing set of organic photocatalysts, displaying no long-range order or extended pi-conjugation. The as-synthesised networks are the sole photocatalytic component, requiring no co-catalyst doping or photosensitiser, representing a highly versatile and exciting platform for solar-energy conversion.</jats:p>

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