As a novel organic semiconductor derived from biomass, hydrothermal carbonation carbon (HTCC) usually exhibits an amorphous structure due to its well-recognized formation pathway based on 5-hydroxymethylfurfural (HMF), which impedes charge transfer and consequently restricts the photocatalytic activity. Herein, we report a crystalline HTCC photocatalyst produced via an unusual synthesis route applied to cellulose in the presence of an oxidant. Notably, the crystalline structure of cellulose was retained and became highly aromatized during the process, leading to significantly enhanced charge transfer efficiency and an increased density of active sites. Moreover, unlike other reported HTCC photocatalysis, the highly active hydrogen radicals (H•) were identified as the dominant active species governing photocatalytic Cr(VI) reduction over crystalline HTCC. As a result, this crystalline HTCC exhibited dramatically enhanced photocatalytic removal efficiencies of Cr(VI) and microcystin-LR (MC-LR) due to the highly efficient charge transfer, abundant active sites as well as highly active hydrogen radicals.
Chen et al. (Sat,) studied this question.