Molybdenum sulfide materials have been shown as promising non-precious catalysts for hydrogen evolution. This paper describes the study of the promotional effects of certain transition metal ions on the activity of amorphous MoS 3 films. Ternary metal sulfide films, M-MoS 3 (M ¼ Mn, Fe, Co, Ni, Cu, Zn), have been prepared by cyclic voltammetry of aqueous solutions containing MCl 2 and (NH 4 ) 2 [MoS 4 ]. Whereas the Mn-, Cu-, and Zn-MoS 3 films show similar or only slightly higher catalytic activity as the MoS 3 film, the Fe-, Co-, and Ni-MoS 3 films are significantly more active. The promotional effects of Fe, Co, and Ni ions exist under both acidic and neutral conditions, but the effects are more pronounced under neutral conditions. Up to a 12-fold increase in exchange current density and a 10-fold increase in the current density at an overpotential of 150 mV are observed at pH ¼ 7. It is shown that Fe, Co, and Ni ions promote the growth of the MoS 3 films, resulting a high surface area and a higher catalyst loading. These changes are the main contributors to the enhanced activity at pH ¼ 0. However, at pH ¼ 7, Fe, Co, and Ni ions appear to also increase the intrinsic activity of the MoS 3 film.

Cu2ZnSnS4 (CZTS) is a promising p-type semiconductor that has not yet been extensively investigated for solar fuel production via water splitting. Here, we optimize and compare two different electrodeposition routes (simultaneous and sequential) for preparing CZTS electrodes. More consistent results are observed with the simultaneous route. In addition, the effect of etching and the presence of a CdS buffer layer on the photocurrent are investigated. Finally, we demonstrate for the first time the stabilization of these electrodes using protecting overlayers deposited by atomic layer deposition (ALD). Our best performing protected electrodes (Mo/CZTS/CdS/AZO/TiO2/Pt) exhibited a photocurrent of over 1 mA cm(-2) under standard one sun illumination conditions and a significant improvement in stability over unprotected electrodes.

Synthesis of metal nanoparticle–graphene composites without the use of any stabilising ligands has enabled the nanoparticle surface to be available for electron transfer reactions in the development of new counter electrodes for solar cells.

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