The photocatalytic oxidation of 1-phenylethanol coupling with hydrogen evolution represents a promising strategy for the full utilization of the photogenerated electrons and holes to accomplish the maximum conversion of solar energy into chemical energy. To date, however, the controllable of reaction path and product distribution has yet not to be unrevealed. Herein, we report an efficient coupled catalytic system composed of ZnIn₂S₄/WO₃ S-scheme heterojunction and Ni-containing polyoxometalate ([Ni₄(H₂O)₂(PW₉O₃₄)₂]¹⁰⁻ (Ni₄P₂)), which exhibited excellent photocatalytic activities towards the oxidation valorization of 1-phenylethanol coupling with hydrogen evolution. The addition of Ni₄P₂ can efficiently control the product distribution. Specifically, 1-phenylethanol was preferentially converted to pinacol (86.0% selectivity) via C–C coupling over ZnIn₂S₄/WO₃ S-scheme heterojunction accompanied by hydrogen production (202.4 μmol), whereas it would be converted to acetophenone (93.8% selectivity) by photogenerated holes with concomitant hydrogen formation (183.1 μmol) over the coupled Ni₄P₂/ZnIn₂S₄/WO₃ catalytic system. Mechanism studies revealed that the hydrogen evolution cocatalyst Ni₄P₂, with its excellent electron storage capacity, can compete with the oxidation product acetophenone for electrons, and thus its addition can significantly inhibit the reduction of acetophenone, resulting in the inability to generate the coupling product pinacol.

In terms of photoelectrochemical (PEC) hydrogen evolution, substantial challenge still remains regarding the controllable fabrication of quantum dots (QDs)-sensitized photocathodes with enhanced visible-light absorption, efficient charge carrier separation, and directional migration at the electrode interface. In this work, the CdTe/CdSe QDs-sensitized photocathodes were delicately constructed on p-type NiO-coated indium tin oxide (ITO) electrodes by spin-coating approach. The resulting co-sensitized photocathode exhibits a favorable pseudo-Type Ⅱ energetic band alignment that combines the advantages of strong light absorption of constituent QDs as well as the effective and oriented charge separation and migration. Upon green LED light illumination, the photogenerated electrons could be effectively transferred to a tetra-nickel-substituted polyoxometalate catalyst for hydrogen production while photogenerated holes will be scavenged at the NiO/ITO electrode. Under minimally optimized conditions, the pseudo-Type Ⅱ CdTe/CdSe-sensitized photocathode yields a photocurrent density of over 100 μA/cm² and a Faradaic efficiency of ~ 100%, which is among one of the most efficient QDs-based photocathode systems coupling with Ni-substituted polyoxometalate catalyst for photoelectrochemical hydrogen generation.