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The p–n type Sm2WO6-Co9S8 heterojunction with two-dimensional coupling interface was successfully synthesized by electrostatic self-assembly. The unique rhombic morphology of Sm2WO6 and Co9S8 nanoparticles also effectively improve the light utilization efficiency. The intervention of Co9S8 enhances the visible light absorption capacity of m2WO6/Co9S8. The Sm2WO6/Co9S8 greatly increases the specific surface area and provides a rich reaction site. Recombination of photogenerated carriers in Sm2WO6/Co9S8 heterojunctions is effectively inhibited. The p–n type Sm2WO6-Co9S8 heterojunction results show that the optimized Sm2WO6/Co9S8 heterojunction exhibits significant hydrogen evolution activity, and the optimal Sm2WO6/Co9S8-25 composite has 117.5 μmol hydrogen evolution activity, it's close to four times Co9S8, close to 143 times Sm2WO6. The stability of the composite Sm2WO6/Co9S8 is the better. Under the built-in electric field induced by p–n heterojunction, using of p–n heterojunction interactions and electron transport modes, the Sm2WO6/Co9S8 can effectively achieve the remarkable effect of its internal carrier separation. This work also provides new opportunities for studying rare earth element tungstate photocatalysts. [ABSTRACT FROM AUTHOR]

The hydrothermal preparation of NiCo 2 S 4 /ZnIn 2 S 4 photocatalysts with different mass ratios is studied. Ni-cobalt bimetallic sulfide nanosheets are grown on zinc-indium bimetallic sulfide to form a compact heterojunction. First, both NiCo 2 S 4 and ZnIn 2 S 4 exhibit N-type semiconductor characteristics, a heterojunction formed by both can reduce the surface reaction energy barrier and use its synergy, strengthening the charge self-diffusion between the two semiconductors, it means the formation of a strong electric field. From the electron transfer path and band structure, NiCo 2 S 4 /ZnIn 2 S 4 has S-scheme heterojunction characteristics. NiCo 2 S 4 is a reducing photocatalyst (RP), and ZnIn 2 S 4 is an oxidative photocatalyst (OP). Under the action of built-in electric field (BIEF), strong photogenic electrons and holes exist in CB of RP (NiCo 2 S 4) and VB of OP (ZnIn 2 S 4). Thus, the overall redox capacity of the NiCo 2 S 4 /ZnIn 2 S 4 heterojunction is enhanced. Using visible light, the composite material can be used for photocatalytic hydrogen production. It is further shown that the composite material has a good effect in photocatalytic hydrogen production under the sensitizer eosin Y (EY) system. The optimal hydrogen production is about 221.75 μmol when the mass ratios of NiCo 2 S 4 /ZnIn 2 S 4 is 20%, and the photocatalytic activity of the composite is about 47 times that of ZnIn 2 S 4. Notably, the stability of the composites is the better. A reasonable photo-catalytic mechanism is proposed based on the band gap and photoelectrochemical properties of heterojunction. • Nanosheets NiCo 2 S 4 innovatively decorated on globular structure ZnIn 2 S 4 form S-scheme heterojunction. • The morphology of nanosheets NiCo 2 S 4 is innovative in the field of NiCo 2 S 4 /ZnIn 2 S 4 photocatalysis. • The heterojunction can short transfer route to promote electron efficient transport. • Dispersion of NiCo 2 S 4 on ZnIn 2 S 4 is important for the heterojunction HER activity and stability. [ABSTRACT FROM AUTHOR]

Photocatalytic hydrogen production was a potential strategy to solve energy shortage and environmental pollution. One of the valuable research directions for improving photocatalytic efficiency was to prepare catalysts in an efficient and low-cost way. Lamellar Sm 2 WO 6 and dodecahedron Zeolitic Imidazolate Framework-67 (ZIF-67) have been prepared successfully based on morphology control. Sm 2 WO 6 /ZIF-67 was prepared by a novel in situ growth scheme, which was confirmed by crystal structure, morphology and elemental composition analysis. The close interaction between Sm 2 WO 6 and ZIF-67 was confirmed by photoelectrochemical measurements. Based on the design of band structure, the S-type heterojunction was constructed. The research results of this paper provided a reference for exploring non-noble metal composite materials and demonstrated great potential in photocatalytic. [Display omitted] • The 3D nanostructured dodecahedron ZIF-67 is prepared. • Sm 2 WO 6 /ZIF-67 is prepared through the in situ growth method. • Sm 2 WO 6 /ZIF-67 photocatalytic hydrogen production activity is improved. • A S-scheme heterojunction is constructed for photocatalysis. • The photocatalysis is enhanced by adjusting the direction of electron transfer. [ABSTRACT FROM AUTHOR]

NiCo-LDH with a layered structure was coupled to Mn 0.2 Cd 0.8 S through electrostatic self-assembly to construct tightly heterojunctioned photocatalysts. The bundles of stacked nanorods and the tightly packed sheets break the agglomeration of each other after electrostatic self-assembly, exposing more redox active sites. The introduction of NiCo-LDH further expands the light absorption of Mn 0.2 Cd 0.8 S towards the visible wavelength range, effectively improving the photoresponse performance. The charge density in NiCo-LDH increases after coupling and the transport direction of photogenerated carriers inside the photocatalyst follows the S-scheme heterojunction migration path. Photogenerated carriers are effectively separated, preserving the more redox-competent conduction band and valence band potentials. The reduction of charge transfer resistance and hydrogen evolution overpotential facilitated the hydrogen evolution reaction. Thus the optimised composite photocatalyst exhibits a significant improvement in hydrogen evolution performance (15.21 mmol·g−1h−1, approximately 28.17 times that of Mn 0.2 Cd 0.8 S) and maintained a good hydrogen evolution stability. [Display omitted] • Tight-contact NiCo-LDH/Mn 0.2 Cd 0.8 S photocatalyst was constructed through electrostatic self-assembly. • Charge transfer path following S-scheme heterojunction of NiCo-LDH/Mn 0.2 Cd 0.8 S is clarified. • Photocatalytic hydrogen evolution activity of NiCo-LDH/Mn 0.2 Cd 0.8 S reached 15.21 mmol·g−1·h−1. • 1D/2D interface enables fast migration of photogenerated carriers. [ABSTRACT FROM AUTHOR]