Photocatalysis has emerged as a green protocol for biorefineries thanks to sustainable energy input. The unique radical mechanism of photocatalysis allows the decomposition of raw biomass and the precise functionalization of platform molecules, but radicals with open-shell electronic structures are highly active, resulting in diverse products. Control of the radical mechanism relies on photocatalysts guiding interfacial charge transfer for chemical bond breaking. The reaction behaviour of radicals and the surface states of semiconductor photocatalysts are therefore crucial for controlling the efficiency and selectivity of biorefineries. Here we discuss the factors that influence the interfacial charge transfer and radical reactions in photocatalytic biorefineries, including the surface structure and electronic states of semiconductors and the catalytic properties of cocatalysts. Recognition of these factors will feed back the expected structure of semiconductors and cocatalysts, assisting with the design of photocatalysts for the efficient and selective refining of native biomass.
Synthesis of fuels and chemicals from renewable biomass is an important way to achieve sustainable development. This Review summarizes catalyst design for steering interfacial charge transfer and radical intermediate reactions in photocatalytic biorefineries.