Synergistically tuning electronic states at the atomic level to facilitate photocatalytic overall water splitting is a challenge. However, elucidation of the role of specific electronic states of Znln 2 S 4 (ZIS) in regulating both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) is still scarce, making it difficult to accurately predict the actual photocatalytic performance. Here, the substitution of Zn sites with Al atoms was found to modulate the potential difference of the ZIS surface domain heterojunction structure, and electrons were further transferred to CuS to form a built-in field that promotes charge separation. When Al doping is present on the ZIS surface, ZIS exhibits p-type semiconductor properties, which leads to the formation of p-n junctions within Al-CuS/ZIS itself. Due to the large work function and metallic properties of CuS, and Al-CuS/ZIS as a whole tends to form a Schottky heterojunction, and the two heterojunction structures synergistically promote the migration of photogenerated carriers. In addition, the Al doping changes the electronic states around the ZIS, allowing the Al ZIS to promote the adsorption of O* and H* during OWS. The solar-driven photocatalytic overall water splitting efficiency of Al-CuS/ZIS is as high as 153.6 (HER) and 73.1 (OER) μmol/h g −1 , which is about 10 times that of ZIS. This work opens the possibility to design efficient photocatalytic materials through tunable composition and electronic structure.
Photocatalysis based on metal sulfide semiconductor is considered as an economic, safe, renewable, and clean technology. However, the availability of photocatalysts is limited by the low solar energy utilization efficiency and the fast recombination of photogenerated electron-hole pairs. Developing a hollow heterostructure photocatalyst based on semiconductors for enhancing solar energy utilization and separation efficiency of photogenerated carriers is crucial in the photocatalytic H 2 production reaction. The as-prepared 3D hierarchical nanocages photocatalyst CuS@ZnIn 2 S 4 with abundant and compact nanosheets 2D/2D hetero-interfaces displayed an improved photocatalytic hydrogen evolution rate as high as 7910 μmol h −1 g −1 in the absence of any cocatalyst. This is the first report of the use of CuS nanosheets-assembled hollow cubic cages to construct 3D hierarchical nanocages photocatalysts. The close distance between the two nanosheet subunits induce the strong interaction, which was advantage to the separation and transfer of charge carriers. In addition, the hollow structure can not only enhance light adsorption, but also suppress photogenerated carrier recombination. The experimental characterizations and theory calculations confirmed that the strong interaction between CuS and ZnIn 2 S 4 2D/2D hetero-interfaces can extremely facilitate the separation of photogenerated charge carriers and accelerate the electrons transfer. The present work provides a feasible method to construct heterojunction photocatalyst for hydrogen evolution via water splitting powered.
Jie Liu,Yingqing Zhan,Xinyue Duan,Jing Yang,Yuxing Han,Yajie Lei,Sihan Li,Hongyi Zhang
The polymeric membrane encounters huge challenge in dealing with high-viscosity oil pollutants and complicated membrane fouling issues. Herein, the multi-functional polymeric composite membrane (ZCP) is fabricated via anchoring bio-adhesive dopamine bridged gear-like CuS–ZnIn 2 S 4 heterostructure onto PAN nanofiber support, which hits three birds with one stone. Firstly, the unique three-dimensional gear-like structure confers the ultra-low oil adhesion and high permeability to membrane by constructing underwater superoleophobicity (UWCA: up to 157.1° ± 1.6°) and providing efficient mass transfer channels, as confirmed by Molecular dynamics simulation and Hermia equation-fitted blocking models. The ZCP membrane demonstrates superior separation flux (3921.44 ± 196.1 L m −2 h −1 ) and separation efficiency (up to 99.53 %) for diverse oil-in-water emulsions. Besides, the ZCP membrane shows remarkable durability in harsh conditions and cyclic separation stability. Secondly, dopamine bridged CuS–ZnIn 2 S 4 heterostructure mitigates charge recombination, strengthens electron transfer, and extends light absorption, which results in favorable photocatalytic self-cleaning via peroxymonosulfate (PMS) activation. Under simulated sunlight and low PMS input, the ZCP membrane exhibits high-efficiency catalytic degradation of organic pollutants within 60 min (97.9 % tetracycline and 100 % dye degradation rates) and effective self-cleaning for membrane regeneration (98.51 ± 2.4 % flux recovery rate). Moreover, the band structure, charge transfer, and mechanism of photocatalytic PMS activation are elucidated. Thirdly, owing to the photothermal conversion function of CuS–ZnIn 2 S 4 heterostructure, the membrane surface temperature reaches 61.7 °C within 15 s, thus efficiently reducing oil viscosity and achieving 102.04 % enhancement in permeation flux during the simulated O/W separation application. This work opens a new avenue for treatment of complex emulsified oily wastewater and membrane fouling control.
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