In Situ Fabrication of Robust Cocatalyst‐Free CdS/g‐C₃N₄ 2D–2D Step‐Scheme Heterojunctions for Highly Active H₂ Evolution

Abstract

Efficient H2O splitting for H2 evolution over the semiconductor photocatalyst is a crucial strategy in the field of energy and environment. Herein, cocatalyst‐free 2D–2D CdS/g‐C3N4 step‐scheme (S‐scheme) heterojunction photocatalysts are fabricated through in situ hydrothermal growth of 2D CdS nanosheets (NSs) on 2D g‐C3N4 NSs. The results clearly confirm that the binary CdS/0.7g‐C3N4 S‐scheme heterojunction shows the best H2 production rate (15.3 mmol g−1 h−1) without using any cocatalyst, which is 3.83 times and 3060 times higher than those of pure CdS and g‐C3N4, respectively. The apparent efficiency of CdS/0.7g‐C3N4 at 420 nm is 6.86%. Importantly, the as‐prepared CdS/0.7g‐C3N4 S‐scheme heterojunction has good stability when continuously irradiated for 21 h. The improved stability and activity are attributed to the formation of the S‐scheme heterojunction, which can markedly accelerate the interfacial charge separation for surface reaction. It is expected that the design of robust cocatalyst‐free CdS/g‐C3N4 2D–2D S‐scheme heterojunction can become a promising approach to develop the highly active H2 evolution systems based on various kinds of conventional semiconductor NSs.

Construction of an Ultrathin S‐Scheme Heterojunction Based on Few‐Layer g‐C3N4 and Monolayer Ti3C2Tx MXene for Photocatalytic CO2 Reduction

“…To achieve the purpose of maintaining the strong redox capacity while improving the carrier separation efficiency, step‐scheme (S‐scheme) photocatalysts are highly desired. [ 20–23 ]…”

2D/2D heterostructured photocatalyst: Rational design for energy and environmental applications

“…Nowadays, the continuous consumption of fossil fuel for industrial manufacturing has caused a terrible growing amount of CO 2 in the atmosphere [159]. It has been reported that the annual anthropogenic CO 2 emissions from fossil fuel combustion have reached at about 9 Gt (1 G=10 9 ), which is approximately 43% higher than the level recorded in pre-industrial times [161,162].…”

“…Ren et al [159] employed 2D CdS to combine with 2D g-C 3 N 4 to form an S-scheme heterojunction for photocatalytic H 2 production. They also demonstrated that the formation of the 2D/2D S-scheme heterojunction could accelerate the interfacial charge separation for surface reaction.…”

Nanostructured CdS for efficient photocatalytic H2 evolution: A review

“…They found that the formation of Z-scheme heterostructures between ZnO and CdS could effectively prolong the lifetime of photogenerated e − , reaching a 14-fold improvement in H 2 evolution performance compared with that of pure CdS. Since then, numerous direct Z-scheme CdS-based photocatalysts have been applied in photo-catalytic H 2 generation applications [334], including CdS/ WO 3−x [222], FeC 2 O 4 •2H 2 O/CdS [335], CdS/WO 3 [165,301], CdS/MoO 3−x [336], CdS/g-C 3 N 4 [337,338], CoWO 4 /CdS [44], CdS/Fe 2 O 3 [179], CdS/BiVO 4 [339], TiO 2 /CdS [329,340,341], CdS/CdWO 4 [219,342], ZnO/ CdS [306] and CdS/PI [217]. In our previous study, we reported the fabrication of 2D/2D CdS/g-C 3 N 4 direct Zscheme heterojunction nanocomposites through the insitu growth of 2D CdS NSs on 2D g-C 3 N 4 NSs [338].…”

“…Notably, coupling semiconductors at their active facets are apparently more promising for efficient photogenerated e − transfer. It is expected that CdS-based composites with 2D/2D layered Z-scheme heterojunctions coupled with their active facets can be rationally fabricated for photocatalytic H 2 evolution [179,338].…”