A selective phosphidation approach was employed to tailor the Cu 3d electron energy in phosphorus-doped carbon nitride (PCN) supported single-Cu-atom catalyst by tuning its coordination environment from Cu1N3 to Cu1P3. Cu1N3@PCN with the d-band center near the Fermi level promoted CO2 photoreduction to CO, while Cu1P3@PCN with a downshifting Cu 3d electron energy favored H2 production via photocatalytic water splitting.
Photoreduction of CO2 into solar fuels has received great interest, but suffers from low catalytic efficiency and poor selectivity. Herein, two single-Cu-atom catalysts with unique Cu configurations in phosphorus-doped carbon nitride (PCN), namely, Cu1N3@PCN and Cu1P3@PCN were fabricated via selective phosphidation, and tested in visible light-driven CO2 reduction by H2O without sacrificial agents. Cu1N3@PCN was exclusively active for CO production with a rate of 49.8 μmolCO gcat
−1 h−1, outperforming most polymeric carbon nitride (C3N4) based catalysts, while Cu1P3@PCN preferably yielded H2. Experimental and theoretical analysis suggested that doping P in C3N4 by replacing a corner C atom upshifted the d-band center of Cu in Cu1N3@PCN close to the Fermi level, which boosted the adsorption and activation of CO2 on Cu1N3, making Cu1N3@PCN efficiently convert CO2 to CO. In contrast, Cu1P3@PCN with a much lower Cu 3d electron energy exhibited negligible CO2 adsorption, thereby preferring H2 formation via photocatalytic H2O splitting.Zum Volltext