Nanocrystalline NiSe2/MoS2 heterostructures for electrochemical hydrogen evolution reaction

Spatially confined synthesis of large-sized MoS2nanosheets in molten KSCN toward efficient hydrogen evolution

Low-temperature KSCN molten salt is a promising technique to synthesize defect-rich MoS2catalysts for hydrogen evolution reaction (HER). However, owing to the fast ion diffusion rate for rapid crystal growth, the resultant catalysts show a morphology of microsphere, which aggregates from MoS2nanosheets, to suppress the catalytic performance. In this work, large-sized few-layer MoS2nanosheets are synthesized via a spatial confinement strategy by adding inert NaCl into the KSCN molten salt. With the NaCl spacer to physically block the long-distance ion diffusion and isolate the chemical reaction, the MoS2nucleation and subsequent crystal growth could be controlled, guiding the nanosheets to grow along the narrow gap between the NaCl crystals to avoid aggregation. As a result, ultrathin MoS2nanosheets with a large geometry size are constructed. Profiting from the architecture to expose active sites and boost charge transfer kinetics, the large-sized few-layer MoS2nanosheets exhibit an impressive HER performance, showing a smallη10of 160 mV and a low Tafel slope of 53 mV dec-1with excellent stability. This work provides not only an efficient HER catalyst but also a facile spatial confinement technique to design and synthesize a large spectrum of transition metal sulfides for broad uses.

Urchin-like PdOs nanostructure for hydrogen evolution electrocatalysis

The compositional and structural engineering of advanced nanomaterials for hydrogen evolution reaction (HER) is highly necessary for efficient hydrogen production. Herein, PdOs nanospine assemblies (PdOs NAs) with urchin-like structures are fabricated via one-step route using DM-970 and KBr as surfactant agent and capping agent, respectively. Benefiting from electronic effect and multi-branched structure, the PdOs NAs exhibit superior performance for HER in alkaline and neutral solutions, requiring overpotentials of 28 and 35 mV at -10 mA cm^-2, respectively, as well as superior long-term stability. This study offers a universal approach for the fabrication of active Pd-based catalysts with multi-branched morphology for efficient water electrolysis and beyond.

Engineering Phase Stability of Semimetallic MoS2 Monolayers for Sustainable Electrocatalytic Hydrogen Production

1T'-phase MoS₂ possesses excellent electrocatalytic performance, but due to the instability of the thermodynamic metastable phase, its actual electrocatalytic effect is seriously limited. Here, we report a wet-chemical synthesis strategy for constructing rGO/1T'-MoS₂/CeO₂ heterostructures to improve the phase stability of metastable 1T' phase MoS₂ monolayers. Importantly, the rGO/1T'-MoS₂/CeO₂ heterostructure exhibits excellent electrocatalytic hydrogen evolution reaction (HER) performance, which is much better than the 1T'-MoS₂ monolayers. The synergistic effects between CeO₂ nanoparticles (NPs) and 1T'-MoS₂ monolayers were systematically investigated. 1T'-MoS₂ monolayers combined with the cocatalyst of CeO₂ NPs can produce lattice strain and distortion on 1T'-MoS₂ monolayers, which can tune the energy band structure, charge transfer, and energy barriers of hydrogen atom adsorption (ΔE_H), leading to promotion of the phase activity and stability of 1T'-MoS₂ monolayers for hydrogen production. Our work offers a feasible method for the preparation of efficient HER electrocatalysts based on the engineering phase stability of metastable materials.

Synergistic optimization promoted overall water splitting of CoSe@NiSe2@MoS2 heterostructured composites

Herein, the preparation of CoSe@NiSe₂@MoS₂ composites and the systematic investigation of their water splitting performance as a function of composition have been demonstrated. CoSe@NiSe₂@MoS₂-12 with the optimized composition exhibits a current density of 10 mA cm^-2 at overpotentials of 81 and 170 mV for HER and OER in alkaline conditions, respectively. The overall water splitting device built using CoSe@NiSe₂@MoS₂-12 exhibited a low voltage of 1.48 V at 10 mA cm^-2 due to the synergistic effects.

Constructing NiSe2@MoS2 nano-heterostructures on a carbon fiber paper for electrocatalytic oxygen evolution

Although MoS2 has shown its potential as an electro-catalyst for the oxygen evolution reaction (OER), its research is still insufficient. In this study, as a novel MoS2-based heterostructure electro-catalyst for OER, namely NiSe2@MoS2 nano-heterostructure, was constructed on a carbon fiber paper (CFP) substrate by a simple approach, which includes electrochemical deposition of NiSe2 film and hydrothermal processing of MoS2 film. In addition to a series of observations on the material structure, electrocatalytic OER performance of NiSe2@MoS2 was fully evaluated and further compared with other MoS2-based OER electro-catalysts. It exhibits an outstanding catalytic performance with an overpotential η 10 of 267 mV and a Tafel slope of 85 mV dec-1. Only 6% loss of current density before and after 10 h indicates its excellent durability. The results indicate that the obtained NiSe2@MoS2 is an excellent OER electro-catalyst and worth exploring as a substitute for noble metal-based materials.