Selective biomass photoreforming for valuable chemicals and fuels: A critical review

Biomass photoreforming represents an attractive and promising approach to produce renewable and sustainable chemicals and fuels. A growing number of investigations aim to selectively attain valuable chemicals and highquality fuels from the abundant biomass via UV/visible-light-driven photocatalysis. However, a cost-effective conversion process for biomass valorization to selective production of valuable chemicals and fuels is still difficult to achieve. This review mainly focuses on photocatalyst development and the effect of experimental conditions for selectivity enhancement of heterogeneous photocatalytic transformations. Photocatalyst development with high selectivity aims to avoid the formation of highly oxidative radicals such as center dot OH that are widely regarded as nonselective species. Electronic band structure and photochemical properties can be tailored to regulate the reaction pathway and selectively produce the desired chemicals via morphology modification, doping, co-catalyst metal loading, and the formation of special crystal facets and phase. The reaction conditions, such as solvent, pH, atmosphere, influence the interaction between photocatalyst and substrate, reaction kinetics, and the solubility of reactive species. The optimization of external factors can improve the reactivity and selectivity. In addition, the utilization of protection chemicals could effectively prevent the formation of destructive radical species and the mineralization of preferred products, thus enhancing the selectivity and productivity. This review provides insights into the photocatalytic upgrading of various biomass substrates to fine chemicals and fuels with an attempt to elucidate the mechanisms involved in the process of biomass photoconversion. Future perspectives and challenges for selective production of valuable chemicals and fuels from biomass photo-upgrading are discussed.

Automated summary

Biomass photoreforming shows potential for producing valuable chemicals and fuels from biomass via UV/visible-light-driven photocatalysis. The key to achieving selectivity lies in the development of photocatalysts and optimization of experimental conditions. Electronic band structure, photochemical properties, and external factors can be tailored to enhance selectivity and productivity in biomass photo-upgrading processes.