NiCS₃: A cocatalyst surpassing Pt for photocatalytic hydrogen production

Cocatalysts play a key role in improving photocatalytic performance by enhancing conductivity and providing an enormous number of active sites simultaneously. However, cocatalysts are usually made of noble metals such as Pt, which are expensive and rare. Therefore, cocatalysts derived from cheap and abundant elements are highly desirable. Here, for the first time, we demonstrate that NiCS₃, which is made from nickel that is abundant and costs less than 0.04 % of Pt, is an effective substitute for Pt cocatalysts for the photocatalytic activity of CdS nanorods in hydrogen evolution reaction (HER). Under visible light, the NiCS₃/CdS composite with NiCS₃ as the cocatalyst achieved an astonishing H₂ production of 61.9 mmol·g^-1·h^-1 while maintaining high stability, which is 14 times higher than that observed when using CdS alone and nearly 2 times higher than that of Pt/CdS. We also established that the metallicity of NiCS₃ results in good carrier conductivity, which promotes the electron transfer and the separation of photo-induced carriers. Due to the appropriate adsorption energy ΔG_H*, NiCS₃ more readily adsorbs hydrogen protons and desorbs molecular hydrogen during the photocatalytic process compared with Pt. Additionally, NiCS₃ can effectively inhibit the photo-corrosion effect of CdS itself, ensuring a good stability of HER. These results suggest that NiCS₃ is a promising substitute for Pt cocatalysts.