Hydrogen evolution from a copper(I) oxide photocathode coated with an amorphous molybdenum sulphide catalyst

Morales‐Guio, Carlos G.; Tilley, S. David; Vrubel, Heron; Grätzel, Michaël; Hu, Xile

doi:10.1038/ncomms4059

Cited by 448 publications

(383 citation statements)

References 26 publications

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“…The H2 and O2 evolution rate of Co3O4/WO3 film is 4.3 μmol/h and 1.9 μmol/h respectively. From the amount of gas evolved and the measured photocurrent, the Faradaic efficiency of the reaction is calculated using Equation 3: 35,36 = ( 2 )/(Q/zF)…”

Section: Resultsmentioning

confidence: 99%

The effect of crystallinity on photocatalytic performance of Co₃O₄ water-splitting cocatalysts

Chua

Ansovini

Lee

et al. 2016

Phys. Chem. Chem. Phys.

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Cocatalysts, when loaded onto a water splitting photocatalyst, accelerate the gas evolution reaction and improve the efficiency of the photocatalyst. In this paper, we report that the efficiency of the photocatalyst is enhanced with an amorphous cobalt oxide cocatalyst. WO3 film, when loaded with amorphous or nanocrystalline Co3O4, shows an improvement of up to 40% in photocurrent generation and 34% in hydrogen gas evolution. The effect of cocatalyst crystallinity on performance was systematically studied, and we found that the photocurrent deteriorates with the conversion of the cocatalyst to highly crystalline phase at annealing temperature of 500 °C. The mechanism for this effect was studied in detail using electrochemical impedance spectroscopy, and the enhancement effect produced by amorphous cocatalyst is attributed to the large density of unsaturated catalytically active sites in the amorphous material.

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Section: Resultsmentioning

confidence: 99%

The effect of crystallinity on photocatalytic performance of Co₃O₄ water-splitting cocatalysts

Chua

Ansovini

Lee

et al. 2016

Phys. Chem. Chem. Phys.

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“…Therefore, we collaborated with the Grätzel group in our institute to apply the MoS 2+x catalyst to promote the photoelectrochemical hydrogen evolution on Cu 2 O. 32 Surface-protected cuprous oxide is arguably the state-of-the-art p-type oxide for photoelectrochemical hydrogen evolution. 33 It has a direct band gap of 2 eV and can produce a maximum photocurrent of 14.7 mA/cm 2 and maximum solar to hydrogen efficiency of 18% under 1 sun irradiation.…”

Section: Promotion Of the Her Activity Of Amorphous Molybdenum Sulfidmentioning

confidence: 99%

Amorphous Molybdenum Sulfides as Hydrogen Evolution Catalysts

2014

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CONSPECTUS:Providing energy for a population projected to reach 9 billion people within the middle of this century is one of the most pressing societal issues. Burning fossil fuels at a rate and scale that satisfy our near-term demand will irreversibly damage the living environment. Among the various sources of alternative and CO 2 -emission free energies, the sun is the only source that is capable of providing enough energy for the whole world. Sunlight energy, however, is intermittent and requires an efficient storage mechanism. Sunlightdriven water splitting to make hydrogen is widely considered as one of the most attractive methods for solar energy storage. Water splitting needs a hydrogen evolution catalyst to accelerate the rate of hydrogen production and to lower the energy loss in this process.Precious metals such as Pt are superior catalysts, but they are too expensive and scarce for large scale applications.In this account, we summarize our recent research in the preparation, characterization, and application of amorphous molybdenum sulfide catalysts for the hydrogen evolution reaction. The catalysts can be synthesized by electrochemical deposition under ambient conditions from readily available and inexpensive precursors. The catalytic activity is among the highest for non-precious catalysts. For example, at a loading of 0.2 mg/cm 2 , the optimal catalyst delivers a current density of 10 mA/cm 2 at an overpotential of 160 mV. The growth mechanism of the electrochemically deposited film catalysts is revealed by an electrochemical quartz microcrystal balance study. While different electrochemical deposition methods produce films with different initial compositions, the active catalysts are the same and are identified as a "MoS 2+x " species. The activity of the film catalysts can be further promoted by divalent Fe, Co, and Ni ions, and the origins of the promotional effects have been probed. Highly active amorphous molybdenum sulfide particles are also prepared from simple wet chemical routes.Electron transport is sometimes slow in the particle catalysts, and an impedance model has been established to identify this slow electron transport. Finally, the amorphous molybdenum sulfide film catalyst has been integrated onto copper(I) oxide photocathode for photoelectrochemical hydrogen evolution. The conformal catalyst extracts efficiently the excited electrons to give an impressive photocurrent density of -5.7 mA/cm 2 at 0 V vs. RHE. The catalyst also confers good stability. INTRODUCTIONSolar irradiation reaching the surface of the Earth in a period of one hour is sufficient to satisfy the world's energy demand for one whole year at the current consumption rate.

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“…In the case of the photoanode, self-oxidation makes it difficult to utilize non-oxide materials. In contrast, the photocathode can be made of a non-oxide material, such as p-type Si [16][17][18][19], copper oxide [20,21], phosphides [22][23][24][25], and oxysulfides [26,27]. Most photocathodes showing a relatively high half-cell solar-to-hydrogen conversion efficiency (HC-STH) [28] have been composed of single-crystalline materials, as in the cases of Si, InP, and InGaP2, owing to their low defect densities; however, these electrodes require time-consuming and costly processes to fabricate.…”

Section: Introductionmentioning

confidence: 99%

Chalcopyrite Thin Film Materials for Photoelectrochemical Hydrogen Evolution from Water under Sunlight

2015

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Abstract:Copper chalcopyrite is a promising candidate for a photocathode material for photoelectrochemical (PEC) water splitting because of its high half-cell solar-to-hydrogen conversion efficiency (HC-STH), relatively simple and low-cost preparation process, and chemical stability. This paper reviews recent advances in copper chalcopyrite photocathodes. The PEC properties of copper chalcopyrite photocathodes have improved fairly rapidly: HC-STH values of 0.25% and 8.5% in 2012 and 2015, respectively. On the other hand, the onset potential remains insufficient, owing to the shallow valence band maximum mainly consisting of Cu 3d orbitals. In order to improve the onset potential, we explored substituting Cu for Ag and investigate the PEC properties of silver gallium selenide (AGSe) thin film photocathodes for varying compositions, film growth atmospheres, and surfaces. The modified AGSe photocathodes showed a higher onset potential than copper chalcopyrite photocathodes. It was demonstrated that element substitution of copper chalcopyrite can help to achieve more efficient PEC water splitting.

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Hydrogen evolution from a copper(I) oxide photocathode coated with an amorphous molybdenum sulphide catalyst

Cited by 448 publications

References 26 publications

The effect of crystallinity on photocatalytic performance of Co₃O₄ water-splitting cocatalysts

The effect of crystallinity on photocatalytic performance of Co₃O₄ water-splitting cocatalysts

Amorphous Molybdenum Sulfides as Hydrogen Evolution Catalysts

Chalcopyrite Thin Film Materials for Photoelectrochemical Hydrogen Evolution from Water under Sunlight

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Hydrogen evolution from a copper(I) oxide photocathode coated with an amorphous molybdenum sulphide catalyst

Cited by 448 publications

References 26 publications

The effect of crystallinity on photocatalytic performance of Co3O4 water-splitting cocatalysts

The effect of crystallinity on photocatalytic performance of Co3O4 water-splitting cocatalysts

Amorphous Molybdenum Sulfides as Hydrogen Evolution Catalysts

Chalcopyrite Thin Film Materials for Photoelectrochemical Hydrogen Evolution from Water under Sunlight

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The effect of crystallinity on photocatalytic performance of Co₃O₄ water-splitting cocatalysts

The effect of crystallinity on photocatalytic performance of Co₃O₄ water-splitting cocatalysts