Tunable CO-to-syngas conversion via strong electronic coupling in S-scheme ZnGaO/g-CN photocatalysts.

The conversion of CO into syngas, a mixture of CO and H, 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 ZnGaO nanodots (∼7 nm) rooted g-CN nanosheets (denoted as ZnGaO/CN) heterojunction photocatalyst was synthesized vis a facial in-situ growth strategy for efficient CO-to-syngas conversion. Both experimental and theoretical studies have demonstrated that the polymeric nature of g-CN and highly distributed ZnGaO nanodots synergistically contribute to a strong interaction between metal oxide and CN support. Furthermore, the desirable S-scheme heterojunction in ZnGaO/CN efficiently promotes charge separation, enabling strong photoredox ability. As a result, the S-scheme ZnGaO/CN exhibited remarkable activity and selectivity in photochemical conversion of CO into syngas, with a syngas production rate of up to 103.3 μ mol g h, even in the absence of sacrificial agents and cocatalyst. Impressively, the CO/H 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-to-syngas conversion with adjustable composition, thus paving the way for new possibilities in sustainable energy conversion and utilization.