Synthesis of P-doped CdS nanorods for efficient blue LED light induced photocatalytic hydrogen evolution

Abstract

Photocatalytic conversion of solar energy to fuel has gained significant attention from the research community as the global energy crisis and environmental concerns are becoming more acute with every passing year. Nonmetal phosphorus (P) doping on CdS materials has a considerable benefit in making efficient photocatalysts for visible light driven hydrogen (H₂) evolution. Here, P-doped CdS (CdS-P) nanorods (NRs) were synthesized by a one-step thermal phosphorization treatment for the photocatalytic hydrogen evolution reaction using lactic acid as the sacrificial agent in the presence of blue and white LED light irradiation. We have authenticated the successful incorporation of P atoms on the CdS NR surface using XPS, XRD, ICP-OES and EDX mapping analyses. The light-dependent photocatalytic activity of CdS-P_0.8 NRs revealed that CdS-P_0.8 NRs have a greater photocatalytic efficiency for the photocatalytic hydrogen evolution reaction in the presence of blue LED light than white LED light. When exposed to blue LED light, CdS-P_0.8 NRs showed an excellent photocatalytic hydrogen production rate of 14.6 mmol g⁻¹ h⁻¹ with a quantum efficiency of 9.5%. The photocatalyst also demonstrates outstanding long term-photostability and recyclability for hydrogen production. Additionally, a high turnover frequency (TOF) of 2.11 h⁻¹ over CdS-P_0.8 is achieved. Due to the P doping in CdS NRs, the photocatalytic performance of CdS-P_0.8 NRs is 28.6 times higher than that of pristine CdS NRs in the presence of blue LED light irradiation. Electrochemical impedance results further ascertained that the outstanding photocatalytic activity of CdS-P_0.8 in comparison with pristine CdS NRs arises from the improvement of charge transfer and separation. The incorporation of P atoms into CdS NRs improved the charge separation efficiency while also preventing the recombination of photogenerated carriers. These findings demonstrate that nonmetal P atoms could be used as a noble metal alternative for the rational construction of prospective photocatalysts in photocatalytic hydrogen production. It also paves the way for the development of semiconductor based photocatalysts with high photocatalytic activity and excellent photostability for practical application.