Mo-activated VC as effective cocatalyst for an enhanced photocatalytic hydrogen evolution activity of CdS

Abstract

Seeking an efficient and stable cocatalyst is of importance for semiconductor-based photocatalytic water splitting to produce hydrogen. In this sense, Mo-activation of VC for better cocatalytic properties was proposed for the first time, aiming to attain improved hydrogen generation of CdS. Our novel, yet facile physical preparation method permits intimate coupling of Mo-activated VC cocatalyst to CdS (through electrostatic attraction force), thereby promises drastic activity enhancement for hydrogen generation. Results indicate the best VC-activating competency of Mo against other transition metals (Co, Fe, Ni, Zn and Cu), which induces highest H2 productivity of CdS after modifying with Mo-activated VC. Under optimum setting, CdS/Mo(0.38)-VC(5 wt%) manifested highest photocatalytic hydrogen production rate of 2267 μmol h−1 g−1, associated to 300 % and 440 % improvement as compared to that of CdS/VC(5 wt%) and pure CdS, respectively. Such activity also outperformed those that yielded by MoSx- or noble metals(Pt, Au or Ag)-co-catalyzed CdS, attributed to the promoted interfacial charges transfer and lowered overpotential of CdS/Mo(0.38)-VC(5 wt%) in hydrogen generation. Correspondingly, high apparent hydrogen production quantum efficiency of 4.3 % was also recorded by the same photocatalyst at 420 nm. In term of stability test, CdS/Mo(0.38)-VC(5 wt%) manifested excellent longevity in 24 h continuous photoreaction and fair recyclability over five consecutive photoreaction cycles. This work provides a new insight to cocatalysts design and synthesis, thereby realizing economic alternatives to precious metal (Pt, Au, Ag) in solar-derived H2 production.