Solar-driven synergistic hydrogen production and benzyl alcohol valorization over Mg-Doped Zn3In2S6

Sunlight-driven valorization of benzyl alcohol (BA) offers a sustainable route to co-produce high-value organic chemicals and green hydrogen, yet the practical deployment of this photocatalytic strategy is severely hindered by unsatisfactory conversion efficiency and product selectivity. Here we report a facile magnesium (Mg) doping strategy to modify Zn 3 In 2 S 6 (abbreviated as ZIS) photocatalysts for boosted photocatalytic BA conversion. Under optimized doping content, the Mg-modified Zn 3 In 2 S 6 (denoted hereafter as Mg-ZIS) enables efficient BA transformation within 1 hour of solar irradiation, achieving a product yield of 94.4% and benzaldehyde (BAD) selectivity of 94%, alongside concurrent hydrogen evolution. The Mg-ZIS exhibits competitive apparent quantum yields (AQY) of 71.68% at 380 ± 20 nm and 16.63% at 420 ± 20 nm for BAD generation. Further analysis indicates that Mg dopants strengthen the Zn-S/In-S covalent bonding, which improves photocarrier separation and their surface accessibility. Mechanistic study further reveals that the exceptional BAD selectivity origins from a slow BAD backward reaction as Mg doping facilitates the competing hydrogen evolution reactions (HER) due to the negatively-shifted band edge alignments. This work validates the efficacy of metal doping in modulating the photocatalytic properties of sulfide-based photocatalysts, and provides a viable paradigm for the rational design and fabrication of high-performance photocatalysts toward efficient organic transformation and coupled hydrogen production.