Visible light-driven photocatalytic H₂ evolution and dye degradation by electrostatic self-assembly of CdS nanowires on Nb₂C MXene

Photocatalytic H₂ evolution and dye degradation using a semiconductor photocatalytic system are considered to be the most appropriate techniques for solving current energy crises and environmental issues. However, the effective separation and utilization of photoexcited charge carriers is the bottleneck of a photocatalytic system. To tackle this problem, we report an efficient photocatalytic system of CdS nanowires (NWs) electrostatically self-assemble on the Nb₂C MXene cocatalyst. The synthesized CdS/Nb₂C composites indicate that the CdS NWs are homogeneous and uniformly distributed on the accordion type Nb₂C MXene cocatalyst, which was confirmed via different characterization techniques such as SEM, TEM, HRTEM, and elemental mapping. Furthermore, the electrochemistry analysis, PL, TRPL, EPR, and UV DRS spectra indicate the synthesized CdS/Nb₂C composites exhibit appreciable enhancement in the separation of photoexcited charge carriers and transfer ability by inhibiting the annihilation factor and improving the light absorption. Therefore, the photocatalytic H₂ evolution efficiency of the optimized CdS/Nb₂C composite reveals 2.53 mmol g⁻¹ h⁻¹, which was 5.34 times superior to CdS NWs. Moreover, the optimized sample manifested efficient stability even after five consecutive cycles and has an apparent quantum efficiency (AQE) of 3.69% with monochromatic light at 420 nm. Furthermore, the optimized CdS/Nb₂C composite also manifests superior performance for photocatalytic degradation of Rhodamine B (RhB), which was a 99% degradation of RhB under light illumination for 20 min, much higher than pristine CdS NWs. This study shows that Nb₂C MXene can be used as a potential noble metal free cocatalyst in a photocatalytic system to overcome environmental and energy crises.