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

Abstract

Abstract 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 Ca2Nb3O10 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. Besides, it is observed that the presence of N-doping contributed towards deposition of higher content of Co-SAs (0.21 wt%) in Ca2Nb3O10-xNx¬-CoSA nanosheets compared to 0.15 wt% for non-doped Ca2Nb3O10-CoSA. The optimized Ca2Nb3O10-xNx-CoSA nanosheets exhibited an impressive photocatalytic O2 evolution of ~727.22 µmol g-1 h-1 via the synergy of N-dopants and Co-SAs. As a result, O2 evolution response of Ca2Nb3O10-xNx-CoSA is 3.6 times higher than pristine Ca2Nb3O10 nanosheets (201.26 µmol g-1 h-1), 2.24 times better than Ca2Nb3O10-xNx nanosheets (323.42 µmol g-1 h-1), and 1.77 times higher compared to Ca2Nb3O10-CoSA, (409.33 µmol g-1 h-1), clearly demonstrated the synergistic effect of N-dopants and Co-SAs in Ca2Nb3O10-xNx-CoSA nanosheets. Base on the finding of various characterization techniques, the co-presence of N-dopants and Co-SAs is observed to contribute towards better charge carriers separation, and utilization to achieve superior photocatalytic response. Thus, this work presents a novel approach for incorporating N-dopants and Co-SAs on Ca2Nb3O10 nanosheets which can be extended to wide range of nanosheets produced by the soft chemical exfoliation method.