Acid‑free photocatalytic acetalization of ethanol to 1,1‑diethoxyethane with concurrent H2 evolution over Ni-decorated ZnIn2S4

Ni-modified ZnIn 2 S 4 for acid-free photocatalytic ethanol acetalization to 1,1-diethoxyethane and H 2 . • Loading the Ni cocatalyst accelerates charge separation, rendering the 1,1-diethoxyethane production rate 14.52 times higher than that of the blank ZIS, while maintaining nearly 100% selectivity. • The acetalization proceeds through the synergistic cooperation of in-situ generated protons and surface Lewis acid sites. Semiconductor-catalyzed acceptor-free dehydrogenative coupling of alcohols has emerged as a promising route for the artificial photosynthesis of high-value acetals. However, competitive activation of O–H and C–H bonds in alcohols causes uncontrolled generation of highly reactive radicals, making it challenging to achieve highly selective acetals production. Herein, we fabricate an efficient photoredox system based on Ni-modified ZnIn 2 S 4 (ZIS), which enables highly selective, acid-free C–O coupling of ethanol to 1,1-diethoxyethane (DEE) with concurrent H 2 evolution. Experimental results demonstrate that Ni modification optimizes the surface electron transport kinetics of ZIS while maintaining excellent DEE selectivity. The in situ-generated protons derived from ethanol dehydrogenation serve as a self-supplied proton source, driving the acetalization between the acetaldehyde intermediate and ethanol, facilitated by Lewis acid sites on the ZIS surface. This work offers some mechanistic insights and rational catalyst design guidelines for acid-free photocatalytic acetal synthesis, thereby enabling the coproduction of value-added chemicals and solar H 2 fuel. Download: Download high-res image (157KB) Download: Download full-size image