Photocatalytic H2 production from aqueous methanol solutions using metal-co-catalysed Zn2SnO4 nanostructures

• Highly crystalline nanosized Zn2SnO4 has been obtained by hydrothermal synthesis.
• Zn2SnO4 itself shows activity for hydrogen production from methanol aqueous solutions.
• When Pt is used as co-catalyst, the H2 production is dramatically improved.
• This enhancement has been addressed to a decrease of the charge recombination rates due to the electron scavenging ability of Pt NPs.
• Au nanoparticles show little activity as co-catalysts for H2 evolution reaction.

The activity of nanocrystalline Zn2SnO4 for photocatalytic hydrogen production from methanol aqueous solutions has been explored. A co-precipitation method starting from metal salts and a mild base as precipitating agent was used to obtain highly crystalline nanosized Zn2SnO4 with cubic inverse spinel structure. In-situ photodeposition of Pt and Au nanoparticles as co-catalysts was performed prior to the photocatalytic reaction. The obtained materials have been characterised by XRD, TEM, N2 adsorption isotherms and ICP-OES, Raman, UV–vis and photoluminescence spectroscopies. Bare Zn2SnO4 gives rise to hydrogen release from a methanol aqueous solution without catalyst deactivation. This photocatalytic activity is remarkably increased with the deposition of platinum. In contrast, the use of gold as co-catalyst increases the activity only slightly, with a lower hydrogen production than a Pt-loaded sample with the same nominal metal content. An improved charge separation and the activity of Pt as hydrogen evolution catalyst are invoked to account for the present findings.

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