Polyoxometalates-mediated hydrogen production from photocatalytic methanol reforming

Photocatalytic hydrogen production from methanol suffers from the sluggish reaction kinetics and low photocatalytic selectivity, as well as the inaccessible on-demand hydrogen production due to the intermittent nature of solar energy. Here, we present a polyoxometalates (POMs)-mediated strategy, acting as photocatalysts and electron-coupled-proton buffers, which not only yields value-added formaldehyde products with high selectivity of almost 100%, but also enables the spatiotemporally decoupled hydrogen production. The photo-reduced POMs exhibit an ultra-low onset oxidation potential (<0 V vs. NHE), thus enabling the direct photocatalytic hydrogen production from methanol in the presence of POMs and Pt/C catalysts with the hydrogen evolution rates of 0.431 mmol h −1  mg −1 Pt and 0.407 mmol h −1  mg −1 Pt in the H 4 SiW 12 O 40 -based and H 6 ZnW 12 O 40 -based systems, respectively. Moreover, an “indirect” methanol fuel cell based on the POM-mediated system can be constructed with an open-circuit voltage of ∼0.9 V and a maximum power density of 33 mW cm −2 .