Catalysts derived from Earth-abundant natural biomass enable efficient photocatalytic CO<inf>2</inf>conversion for achieving a closed-loop carbon cycle

Photocatalytic carbon dioxide (CO2) conversion is a promising technology to address the greenhouse effect and energy shortage problems by utilizing the inexhausted solar energy. However, the over-reliance on metal-based photocatalysts hampers its long-term application. Here, a series of Earth-abundant natural biomass-derived heteroatom-doped carbonaceous photocatalysts prepared via a sulfuric-acid-assisted carbonization method are developed to convert the CO2 waste into the valuable carbon monoxide (CO) fuel. On account of visible-light-harvesting, large CO2 uptake, efficient charge separation and abundant defects, green catalysts such as the carbonized konjac biomass (CKB) exhibit a superior visible-light-driven CO formation of 115 μmol g-1 h-1 without using any co-catalyst or sacrificial reagent. The versatility of the synthetic approach developed is verified by preparing a series of carbonaceous photocatalysts derived from various Earth-abundant natural biomass precursors including crops, plants, and agricultural waste. The results show that they all perform appreciable photocatalytic CO2-to-CO conversion. This study provides a general method for designing cheap, high-performance, sustainable, and metal-free photocatalysts using natural biomass, which makes the large-scale practical use feasible and helps achieve a closed-loop carbon cycle. This journal i