Synergy of nitrogen dopants and cobalt single atoms in calcium niobate nanosheets for photocatalytic oxygen evolution

Abstract The successful separation of photoexcited charge carriers and their effective utilization are crucial for overcoming the slow kinetics of the four-electron process for photocatalytic oxygen evolution. Herein, a novel strategy utilizing urea as a source of N-doping on Ca 2 Nb 3 O 10 nanosheets is adopted, followed by the successful deposition of Co single atoms (Co-SAs) to achieve a synergistic effect. The presence of N-dopants and Co-SAs is validated via various experimental techniques. It is also observed that the presence of N-doping contributed towards the deposition of higher content of Co-SAs (0.21 wt%) in Ca 2 Nb 3 O 10− x N x -Co SA nanosheets compared to 0.15 wt% for non-doped Ca 2 Nb 3 O 10 -Co SA . The optimized Ca 2 Nb 3 O 10− x N x -Co SA nanosheets exhibited an impressive photocatalytic O 2 evolution of ∼727.22 µ mol g −1 h −1 via the synergy of N-dopants and Co-SAs. As a result, the O 2 evolution response of Ca 2 Nb 3 O 10− x N x -Co SA is 3.6 times higher than that of pristine Ca 2 Nb 3 O 10 nanosheets (201.26 µ mol g −1 h −1 ), 2.24 times better than Ca 2 Nb 3 O 10− x N x nanosheets (323.42 µ mol g −1 h −1 ), and 1.77 times higher compared to Ca 2 Nb 3 O 10 -Co SA , (409.33 µ mol g −1 h −1 ), which clearly demonstrated the synergistic effect of N-dopants and Co-SAs in Ca 2 Nb 3 O 10− x N x -Co SA nanosheets. Based on the findings of various characterization techniques, the co-presence of N-dopants and Co-SAs is observed to contribute towards better charge carrier separation, and utilization to achieve superior photocatalytic response. Thus, this study presents a novel approach for incorporating N-dopants and Co-SAs on Ca 2 Nb 3 O 10 nanosheets, which can be extended to a wide range of nanosheets produced by the soft chemical exfoliation method.