Rational design of a Z-scheme 2D/2D S-doped g-C3N4/Bi2MoO6 heterostructure for enhanced photocatalytic CO2 reduction to CH3OH

The photocatalytic performance of graphitic carbon nitride (g-C 3 N 4 ) in the conversion of CO 2 to CH 3 OH is intrinsically constrained by its limited selectivity and activity. Herein, we developed a dual-modification strategy that integrates S doping into the g-C 3 N 4 (CN) skeleton and constructed a 2D/2D S-doped g-C 3 N 4 /Bi 2 MoO 6 Z-scheme heterojunction (SCN/BMO) via microwave-assisted synthesis. This strategy achieved sulfur doping through N-site substitution to modulate the electronic structure of CN, resulting in the formation of a 2D/2D SCN/BMO Z-scheme heterojunction. The optimized 0.3SCN/BMO photocatalyst achieved a methanol production rate of 6.19 μmol·g −1 ·h −1 with 99.15 % selectivity under solar irradiation, showing a 5.16-fold and 2.60-fold enhancement in catalytic activity compared to pristine g-C 3 N 4 and Bi 2 MoO 6 (BMO), respectively. Meanwhile, it demonstrated excellent photocatalytic and structural stability during the cycling tests. Systematic characterization analyses have revealed that the synergistic light-harvesting effect, optimized interfacial coupling, and efficient charge transport pathways within the 2D/2D 0.3SCN/BMO Z-scheme heterostructure collectively contribute to the significant enhancement in photocatalytic performance. Moreover, a feasible photocatalytic mechanism has been put forward by combining the outcomes of in-situ DRIFT spectroscopic analysis with DFT computational modeling. This research finding provides an innovative strategy for the development of highly efficient photocatalysts, which are specifically designed for the selective reduction conversion of CO 2 to CH 3 OH.