Enhanced π-electron transport in graphitic carbon nitride (g-C3N4) by constructing biochar-welded donor-acceptor (D-A) configuration for photocatalytic conversion of biomass

g-C3N4 has broad prospects in photocatalytic upgrading of biomass but suffers from the large exciton binding energy and high charge recombination rate. Herein, we integrated the biomass-derived carbocyclic rings with heptazine units via π-conjugation, constructing biochar-welded electron donor (D)-acceptor (A) structures in g-C3N4. This structure can induce intrinsic driving forces that promoted electron delocalization and transport. Meanwhile, the interlayer π-π stacking interaction of the carbocyclic rings provided a channel for electrons to migrate on the vertically layered structure. The g-C3N4 with biochar-welded D-A configuration exhibited an improved yield of 87.52% for xylonic acid from biomass monosaccharide. The mechanism study confirmed the dominant role of superoxide radicals (·O2-) and distinguished singlet oxygen (1O2) from the generation path, demonstrating the supporting role of 1O2 originated from an energy transfer process. This work proposed a universal strategy to construct g-C3N4-based photocatalysts with D-A configuration to achieve efficient photocatalytic reforming of biomass.