Construction of CoS₂/Zn_0.5Cd_0.5S S‐Scheme Heterojunction for Enhancing H₂ Evolution Activity Under Visible Light

Abstract

In the field of photocatalysis, building a heterojunction is an effective way to promote electron transfer and enhance the reducibility of electrons. Herein, the S-scheme heterojunction photocatalyst (CoS 2 /Zn 0.5 Cd 0.5 S) of CoS 2 nanospheres modified Zn 0.5 Cd 0.5 S solid solution was synthesized and studied. The H 2 evolution rate of the composite catalyst reached 25.15 mmol g À 1 h À 1 , which was 3.26 times that of single Zn 0.5 Cd 0.5 S, whereas pure CoS 2 showed almost no hydrogen production activity. Moreover, CoS 2 /Zn 0.5 Cd 0.5 S had excellent stability and the hydrogen production rate after six cycles of experiments only dropped by 6.19 %. In addition, photoluminescence spectroscopy and photoelectrochemical experiments had effectively proved that the photogenerated carrier transfer rate of CoS 2 /Zn 0.5 Cd 0.5 S was better than CoS 2 or Zn 0.5 Cd 0.5 S single catalyst. In this study, the synthesized CoS 2 and Zn 0.5 Cd 0.5 S were both n-type semiconductors. After close contact, they followed an S-scheme heterojunction electron transfer mechanism, which not only promoted the separation of their respective holes and electrons, but also retained a stronger reduction potential, thus promoting the reduction of H + protons in photocatalytic experiments. In short, this work provided a new basis for the construction of S-scheme heterojunction in addition to being used for photocatalytic hydrogen production.

Study of the different morphologies of Zn0.5Cd0.5S for photocatalytic H2 production

“…These can consume excessive e − or h + , promoting the rapid and efficient separation of PCCs. For H 2 evolution, some sacrificial agents are commonly added, such as methanol, 41 lactic acid, 42–44 triethanolamine, 45,46 glucose, 47 or Na 2 S/Na 2 SO 3 . 48 They can neutralize the photogenerated h + , which are positively charged and strongly oxidizing during the photoreaction process, thereby resulting to the known photocorrosion phenomenon.…”

“…These can consume excessive e − or h + , promoting the rapid and efficient separation of PCCs. For H 2 evolution, some sacricial agents are commonly added, such as methanol, 41 lactic acid, [42][43][44] triethanolamine, 45,46 glucose, 47 or Na 2 S/Na 2 SO 3 . 48 They can neutralize the photogenerated h + , which are positively charged and strongly oxidizing during the photoreaction process, To enhance the PCCs utilization of several of the ZCS samples, some sacricial agents were added into the reaction system, including formic acid, lactic acid, and Na 2 S/Na 2 SO 3 .…”

Graphdiyne/Ag2Mo2O7 S‐Scheme Heterojunction for Photocatalytic Hydrogen Production Promoted with Efficient Photogenerated Carriers Separation

“…This contributes a tactics to effectively enhance the photocatalytic hydrogen-producing ability by solving the problem of serious recombination of photogenerated carriers. [37][38][39] 2. Experimental Section The catalyst Ag 2 Mo 2 O 7 was prepared by hydrothermal synthesis.…”

Construction of one-dimensional ZnCdS(EDA)/Ni@NiO for photocatalytic hydrogen evolution

“…7 The loaded cocatalyst can promote the separation and migration of the photogenerated charge on the semiconductor, providing a more active site for the water splitting reaction and improving the photo-corrosion resistance and stability of the photocatalyst. It has been realized that most of the methods for separating the photogenerated electrons and holes are via the construction of heterojunctions between ZnCdS and compounds such as Fe 2 O 3 , 8 Cu 2 S, 9 CoS 2 , 10 Mo 3 S 4 , 11 NiO, 12 etc .…”