Recent trends and optimization strategies for CdS-based photocatalysts: A scale-up approach for efficient solar fuel (hydrogen) generation

Providing renewable and inexpensive energy sources via photocatalytic water splitting to produce hydrogen relies on fabrication of efficient and stable photocatalyst. Cadmium sulfide (CdS), a typical metal sulfide semiconductor photocatalyst has witnessed considerable exploration for its narrow band gap, attractive band positions and strong photocatalytic driving force. However, the main challenge is its instability due to photocorrosion. In this review, we explore the latest strategic approach of optimizing the efficiency of CdS-based photocatalysts toward commercialization of hydrogen production via water splitting. The fundamental semiconductor properties of CdS including its synthesis methods are reported. Recent progress and advances in the various approaches for enhancing the efficiency of CdS-based photocatalysts have been discussed. Findings reveal that the efficiency and hydrogen production rate of CdS-based photocatalyst can be significantly improved through heterojunction formation, co-calatyst incorporation, morphology modulation and designing a covering layer etc. Furthermore, employing compounded modification strategies is a surest way to harness the photocatalytic advantages of CdS. Commercial application of photocatalytic hydrogen production is feasible, albeit not economically competitive compared to other methods. Thus, scientific and engineering advancements are required to actualize its economic viability in hydrogen generation. So far, CdS-based photocatalytic hydrogen production reach up to 500 mmolg- 1h- 1 in a laboratory scale and 1.88 Lh-1 in an up scaled level. A brief future perspective on photocatalytic hydrogen production using CdS is outlined.