N-Doped Carbon Layer Encapsulated NiP for Photocatalytic Alcohol Oxidation Coupled Hydrogen Evolution on Ag-In-Zn-S...

The photocatalytic oxidation of alcohols to value-added chemicals with simultaneous hydrogen (H₂) generation is a promising sustainable process that suffers from slow charge transfer and poor integration of both reactions. Here, an NH₂-containing Ni metal-organic framework (MOF) is used as a precursor for creating N-doped C layer encapsulated nickel phosphide (NiP@NC), which effectively enhances the charge transfer and reaction coupling when modified on narrow-band-gap Ag-In-Zn-S quantum dots (AIZS QDs). The resulting AIZS/NiP@NC photocatalysts demonstrate high efficiency for benzyl alcohol (BA) oxidation coupled H₂ evolution, achieving H₂/benzaldehyde production rates of 9.66/5.67 mmol g^-1 h^-1, which are 3.30 and 47.25 times higher than those of pure AIZS QDs, respectively. Additionally, the selectivity of benzaldehyde is enhanced to 77.96%. AIZS/NiP@NC also shows improved performance for other organics, including 4-methoxybenzyl alcohol and biomass-derived furfuryl alcohol. Photoelectrochemical and transient photovoltage spectroscopy tests confirm the increased effective surface charges and charge transfer efficiency, while electron paramagnetic resonance spectroscopy reveals a carbon-centered radical pathway for selective benzaldehyde formation. DFT calculations suggest that the N-doped carbon enhances the proton adsorption on Ni sites and BA adsorption on the NiP@NC surface. This work highlights the potential of multifunction integration in developing carbon-based cocatalysts for photocatalytic alcohol oxidation coupled H₂ evolution.