Enhancing Hydrogen Evolution Reaction Activities of 2H-Phase VS2 Layers with Palladium Nanoparticles

Construction of Ni3+-rich nanograss arrays for boosting alkaline water oxidation

The rational design of high-efficiency electrocatalysts for application in water oxidation in alkaline media remains a great challenge. In this paper, Ni³⁺-rich nanograss-like Mo-doped Ni₃S₂/NiS/VS arrays grown on nickel foam (denoted as Mo-NiVS@NF) have been successfully constructed through a hydro/solvothermal method. Interestingly, Mo-NiVS@NF exhibits superior catalytic OER performance, needing an overpotential of 217 mV to drive a current density of 10 mA cm^-2, outperforming most previously reported NiS-based electrocatalysts. The result indicates that the Ni³⁺-rich active sites caused by the modulation of the electronic structure environment via the introduction of V and high-valency Mo play an important role in the high activity for the OER. Moreover, this catalyst shows high long-term electrochemical durability.

Accelerated discovery of superoxide-dismutase nanozymes via high-throughput computational screening

The activity of nanomaterials (NMs) in catalytically scavenging superoxide anions mimics that of superoxide dismutase (SOD). Although dozens of NMs have been demonstrated to possess such activity, the underlying principles are unclear, hindering the discovery of NMs as the novel SOD mimics. In this work, we use density functional theory calculations to study the thermodynamics and kinetics of the catalytic processes, and we develop two principles, namely, an energy level principle and an adsorption energy principle, for the activity. The first principle quantitatively describes the role of the intermediate frontier molecular orbital in transferring electrons for catalysis. The second one quantitatively describes the competition between the desired catalytic reaction and undesired side reactions. The ability of the principles to predict the SOD-like activities of metal-organic frameworks were verified by experiments. Both principles can be easily implemented in computer programs to computationally screen NMs with the intrinsic SOD-like activity.

Electrospun Cobalt-Incorporated MOF-5 Microfibers as a Promising Electrocatalyst for OER in Alkaline Media

Metal-organic framework (MOF)-based materials have attracted attention in recent times owing to their remarkable properties such as regulatable pore size, high specific surface area, and elasticity in their network topology, geometry, dimension, and chemical functionality. It is believed that the incorporation of a MOF network into a fibrous matrix results in the improvement of the electrocatalytic properties of the material. Herein, we have synthesized a Co-incorporated MOF-5-based fibrous material by a simple wet-chemical method, followed by an electrospinning (ES) process. The as-prepared Co-incorporated MOF-5 microfibers were employed as an electrocatalyst for the oxygen evolution reaction (OER) in 1 M KOH electrolyte. The catalyst demands a lower overpotential of 240 mV to attain a current density of 10 mA/cm² with a lower Tafel slope value of 120 mV/dec along with a charge transfer resistance value of 2.9 Ω from electron impedance spectroscopy (EIS) analysis. From these results, it has been understood that the incorporation of Co metal into the MOF-5 microfibrous network has significantly improved the OER performance, which made them a potential entrant in other energy-related applications also.

Fe doped amorphous single layered vanadyl phosphate nanosheets as highly efficient electrocatalyst for water oxidation

The search for earth-abundant water oxidation electrocatalysts with low-cost and high-performance is essential to the energy conversion field. Well defined, rational designed two-dimensional materials have attracted enormous interest in light of much more specific surface areas and unique electronic properties. Herein, we report a facile two-phase solvothermal approach for the synthesis of Fe doped amorphous single-layered (~0.85 nm) vanadyl phosphate nanosheets (Fe-Am VOPO₄). The obtained electrocatalyst exhibits excellent OER electrocatalytic performance, only require overpotential of 215 mV and 270 mV to reach current densities of 10 and 100 mA cm^-2 in 1.0 M KOH electrolyte, and long-term electrochemical stability of 40 h. This work strikes out a path of synthesis of graphene-like materials with amorphous phase, and explores a new type of phosphate for efficient OER electrocatalysts.

Rational Design and Controlled Synthesis of V-Doped Ni3 S2 /Nix Py Heterostructured Nanosheets for the Hydrogen Evolution Reaction

Rational construction of high-efficiency and low-cost catalysts is one of the most promising ways to produce hydrogen but remains a huge challenge. Herein, interface engineering and heteroatom doping were used to synthesize V-doped sulfide/phosphide heterostructures on nickel foam (V-Ni₃ S₂ /Ni_x P_y /NF) by phosphating treatment at low temperature. The incorporation of V can adjust the electronic structure of Ni₃ S₂ , expose more active sites, and protect the 3D structure of Ni foam from damage. Meanwhile, the heterogeneous interface formed between Ni₃ S₂ and Ni_x P_y can provide abundant active sites and accelerate electron transfer. As a result, the V-Ni₃ S₂ /Ni_x P_y /NF nanosheet catalyst exhibits outstanding activity in the hydrogen evolution reaction (HER) with an extremely low overpotential of 90 mV at a current density of 10 mA cm^-2 and stable durability in alkaline solution, which exceeds those most of the previously reported Ni-based materials. This work shows that rational design by interfacial engineering and metal-atom incorporation has a significant influence for efficient hydrogen evolution.