Enhanced Visible‐Light Photocatalytic H₂ Production by Zn_xCd_1−xS Modified with Earth‐Abundant Nickel‐Based Cocatalysts

Abstract

The application of various earth-abundant Ni species, such as NiS, Ni, Ni(OH)2 , and NiO, as a co-catalyst in a Znx Cd1-x S system for visible-light photocatalytic H2 production was investigated for the first time. The loading of Ni or NiS enhanced the photocatalytic activity of Znx Cd1-x S because they could promote the electron transfer at the interface with Znx Cd1-x S and catalyze the H2 evolution. Surprisingly, Ni(OH)2 -loaded Znx Cd1-x S exhibits a very high photocatalytic H2 -production rate of 7160 μmol h(-1) g(-1) with a quantum efficiency of 29.5 % at 420 nm, which represents one of the most efficient metal sulfide photocatalysts without a Pt co-catalyst to date. This outstanding activity arises from the pronounced synergetic effect between Ni(OH)2 and metallic Ni formed in situ during the photocatalytic reaction. However, the loading of NiO deactivated the activity of Znx Cd1-x S because of their unmatched conduction band positions. This paper reports the optimization of the Znx Cd1-x S system by selecting an appropriate Ni-based co-catalyst, Ni(OH)2 , from a series of Ni species to achieve the highest photocatalytic H2 -production activity for the first time and also reveals the roles of these Ni species in the photocatalytic activity.

Nickel-based cocatalysts for photocatalytic hydrogen production

“…In addition to sulfides and phosphides, several Ni-based oxides and hydroxides, such as NiO, NiO x and Ni(OH) 2 , are also well-known as highly active cocatalysts after being integrated with semiconductors for photocatalytic H 2 production [63][64][65][66][67][68][69][70][71][72][73][74][75][76][77], as summarized in Table 3. For example, Chen et al showed that in situ photodeposition of NiO x on CdS could enhance its photocatalytic H 2 generation activity [63].…”

“…In a recent example, Ran et al compared the different activities of various Ni-based materials (i.e. NiS, Ni, Ni(OH) 2 , and NiO) as cocatalysts in combination with Zn x Cd 1−x S for visible-light-driven H 2 production [73]. It has been revealed that the types of the cocatalyst could strongly influence the photocatalytic activity of Zn x Cd 1−x S. Among various cocatalysts investigated, Ni(OH) 2 -loaded Zn x Cd 1−x S composite photocatalysts displayed the highest activity due to the synergetic effect between Ni(OH) 2 and metallic Ni formed by in situ photoreduction of a certain percentage of Ni 2+ in Ni(OH) 2 , achieving a H 2 -production rate as high as 7160 mol h −1 g −1 and a QE of 29.5% at 420 nm using TEOA as a sacrificial electron donor.…”

“…In particular, Ni-based materials demonstrate excellent activity and have received much attention as H 2 -evolution cocatalysts. Many kinds of Ni-based cocatalysts, such as metallic Ni [38][39][40][41][42][43][44][45][46][47][48][49], sulfides [50][51][52][53][54][55][56][57][58][59][60][61], phosphides [62], oxides [63][64][65][66][67][68][69], hydroxides [70][71][72][73][74][75][76][77], hydrogenases [78][79][80][81], as well as molecular complexes [81][82][83][84][85][86]…”

Single‐Crystal Semiconductors with Narrow Band Gaps for Solar Water Splitting

“…[36] However,the scarcity and high costs of these noble-metal-based cocatalysts have hindered their application on al arge scale.T hus,t he design and development of non-noble water splitting cocatalysts with high efficiencyish ighly desired. [37] …”

Fluorescein supramolecular nanosheets: A novel organic photocatalyst for visible-light-driven H2 evolution from water

“…4d). This photocorrosion is very common for many oxides, nitride and sulfides semiconductor photocatalysts, involving ZnO [43,44], CdS [45,46], Zn x Cd 1-x S [47], TaON [48]; and similar strategies, such as composites with graphene, more suitable sacrificial agent, surface coating protection, will be adopted to enhance photocatalytic stability of supramolecular NSs.…”