Synergistic effects on d-band center via coordination sites of M-N3P1 (M = Co and Ni) in dual single atoms that enhances photocatalytic dechlorination from tetrachlorobispheonl A

Transition metal single atoms (TM-SAs) coordinated with highly electronegative N atoms often suffer from low activity and poor stability, which limiting their application in catalysis. To solve it, a PH3-assisted annealing strategy is designed to synthesize atomically dispersed TM-SAs (CCoNiP), which is stemmed from a pyrolysis approach of pre-designed CoNi layered double hydroxide (LHD) as a soft-template, and further coordinated with P atoms for adjusting the coordination environment. Characterization results show that the atomically dispersed Co and Ni atoms anchor on the carbon nitride substrate with Co/Ni-N3P1 coordination sites. Combined with density functional theory calculations, it is confirmed that multiple coordination sites of Co/Ni-N and Co/Ni-P can modulate d-band center position which increases the catalytic activity of TM-SAs. The formed multiple midgap levels can extend optical absorption ranges. Meanwhile, P-introduction can change the coordination environment, suppress the conversion trend of SAs to high valence state and improve electron separation. All the above characteristics can improve effective degradation from Tetrachlorobisphenol A (TCBPA) under visible light irradiation, achieving 100% removal and 44.1% dechlorination rate.