Photocatalytic selective C-C bond cleavage of biomass-based monosaccharides and xylan to co-produce lactic acid and CO over an Fe-doped GaN catalyst

The utilization of photocatalysis for the simultaneous production of valuable fine chemicals and fuels from biomass-derived feedstocks holds significant promise; however, its practical implementation remains constrained. In this study, we present the development of an Fe-doped gallium nitride (GaN) catalyst treated by calcination (Fe@GaN-X) for the selectively conversion of biomass-based monosaccharides and xylan into lactic acid and carbon monoxide (CO). Fe@GaN-400 exhibited broader visible light absorption, lower resistance, and reduced photoluminescence intensity in comparison to pristine GaN, thereby affording exceptional photocatalytic activity (lactic acid yield: 71.38%; CO evolution rate: 385.74 μmol g−1 h−1). When monosaccharides and xylan were used as substrates, the Fe@GaN-400 system demonstrated outstanding photocatalytic activity, particularly in the case of xylan system (CO evolution rate = 923.21 μmol g−1 h−1). Additionally, the experimental results revealed the generation of distinctive reactive species, encompassing holes (h+), superoxide anion (·O2-), hydroxyl radical (·OH) and singlet oxygen (1O2) within this catalytic system. Remarkably, the ·O2- and h+ exhibit heightened selectivity towards CO and lactic acid, respectively. This work establishes a novel pathway for the co-production of fine chemicals and fuels through the photocatalytic conversion of biomass.