Enhanced photoelectric performance of ZnFe₂O₄ catalysts for oxidative carboxylation of styrene by tuning crystal planes and thermal and electrical conductivity

The photocatalytic oxidative carboxylation to yield cyclic carbonates was a promising approach for value-added utilization of olefins. Herein, various ZnFe₂O₄ (ZFO) based catalysts with different morphologies and supports were successfully prepared. Layered ZFO exposed highly active (422) crystal planes, which endowed the catalyst with narrow band gap and favorable electron transfer and charge separation, thereby promoting photocatalytic styrene epoxidation. Consequently, a 95 % selectivity for styrene oxide along with the complete conversion of styrene was achieved. Graphene with excellent electrical and thermal conductivity was compounded into ZFO based catalysts. On the one hand, ZFO/Graphene hybrids composed of 50 wt% graphene promoted fast charge transport in oxygen evolution reaction (OER), and the OER performance was comparable to the commercial RuO₂ electrocatalyst. On the other, it exhibited significant photothermal effect and used into CO₂ cycloaddition, delivering 95 % selectivity for styrene carbonate at a styrene oxide conversion of 95 %. As a result, a coupled photo-electro-heterogeneous catalytic system was proposed to yield styrene carbonate over ZFO based catalysts, including OER, styrene epoxidation and CO₂ cycloaddition. This study provided an effective avenue for designing and fabricating ZFO based catalysts by crystal plane and support control.