Tunable CO2-to-syngas conversion via strong electronic coupling in S-scheme ZnGa2O4/g-C3N4 photocatalysts

The conversion of CO 2 into syngas , a mixture of CO and H 2 , via photocatalytic reduction , is a promising approach towards achieving a sustainable carbon economy. However, the evolution of highly adjustable syngas, particularly without the use of sacrifice reagents or additional cocatalysts, remains a significant challenge. In this study, a step-scheme (S-scheme) 0D ZnGa 2 O 4 nanodots (∼7 nm) rooted g-C 3 N 4 nanosheets (denoted as ZnGa 2 O 4 /C 3 N 4 ) heterojunction photocatalyst was synthesized vis a facial in-situ growth strategy for efficient CO 2 -to-syngas conversion. Both experimental and theoretical studies have demonstrated that the polymeric nature of g-C 3 N 4 and highly distributed ZnGa 2 O 4 nanodots synergistically contribute to a strong interaction between metal oxide and C 3 N 4 support. Furthermore, the desirable S-scheme heterojunction in ZnGa 2 O 4 /C 3 N 4 efficiently promotes charge separation, enabling strong photoredox ability. As a result, the S-scheme ZnGa 2 O 4 /C 3 N 4 exhibited remarkable activity and selectivity in photochemical conversion of CO 2 into syngas, with a syngas production rate of up to 103.3 μ mol g −1 h −1 , even in the absence of sacrificial agents and cocatalyst. Impressively, the CO/H 2 ratio of syngas can be tunable within a wide range from 1:4 to 2:1. This work exemplifies the effectiveness of a meticulously designed S-scheme heterojunction photocatalyst for CO 2 -to-syngas conversion with adjustable composition , thus paving the way for new possibilities in sustainable energy conversion and utilization.