Solution-Processed Cu₂S Photocathodes for Photoelectrochemical Water Splitting

Abstract

Cu 2 S has been regarded as a promising solar energy conversion material because of its favorable visible light absorption and earth abundance. Here, we present an indirect preparation method via a solution-processed ion exchange reaction to synthesize stoichiometric Cu 2 S films with high photoactivity. In addition, we developed a chemical bath deposition method to fabricate CdS buffer layers on Cu 2 S by adding a reducing agent in the precursor solution, avoiding oxidation of Cu 2 S. After being coated with the TiO 2 protection layer and the RuO x hydrogen evolution catalyst, the Cu 2 S photoelectrode delivers a photocurrent density of 7.0 mA cm −2 at −0.3 V vs RHE and an onset potential of 0.48 V vs RHE under AM 1.5G simulated sunlight illumination for solar driven water reduction. To our knowledge, this is the first time that Cu 2 S has been used for solar hydrogen evolution with encouraging performance, which will stimulate further studies on Cu-based photocathodes.

Benchmark performance of low-cost Sb2Se3 photocathodes for unassisted solar overall water splitting

“…the formation of undesirable detrimental phases during processing, could pose a major obstacle to large-scale commercialisation. In recent years, various low-cost semiconductors have emerged, such as Cu 2 S (E g~1 .5 eV) 13 , CuFeO 2 (E g~1 .5 eV) 14 , CuBi 2 O 4 (E g~1 .7 eV) 15 , CuSbS 2 (E g~1 .5 eV) 16 , and SnS (E g~1 .3 eV) 17 . However, none of them have satisfied all the requirements for an ideal semiconductor for PEC water splitting.…”

Recent Advances in Earth‐Abundant Photocathodes for Photoelectrochemical Water Splitting

“…In addition, p‐type semiconductors with smaller band gaps should also be explored for combination with other low‐cost, wide band gap, n‐type semiconductors, such as TiO 2 (≈3.2 eV), WO 3 (≈2.8 eV), and BiVO 4 (≈2.4 eV). In this regard, Cu 2 S, with a smaller band gap of 1.47 eV, was recently reported as a photocathode material for PEC water splitting . Although the performance of the first Cu 2 S photocathode (6 mA cm −2 at 0 V versus RHE, onset potential of 0.48 V versus RHE) was inferior to the state‐of‐the‐art Cu 2 O photocathode, it has potential for improvement upon further investigation, considering its relatively short history.…”

Current perspectives in engineering of viable hybrid photocathodes for solar hydrogen generation

“…figure 9). The same concept was also successfully applied for the deposition of noble metal oxides like RuO 2 [41,43], or metal alloy catalysts like NiMo [46]. As the catalyst is resulted from the reduction of an appropriate precursor induced by the photogenerated electrons, it is well located on the hot-pot of the light harvester surface.…”