MoS 2 -based transition-metal chalcogenides are considered as cost-effective, highly active, and stable materials with great potential in the application of electrocatalytic hydrogen production. However, their limited quantity of active sites and poor conductivity have hampered the efficiency of hydrogen production. Combining calculations and experiments, we demonstrate that P dopants could be the new active sites in the basal plane of MoS 2 and help improve the intrinsic electronic conductivity, leading to a significantly improved activity for hydrogen evolution. Furthermore, the P-doped MoS 2 nanosheets show enlarged interlayer spacing, facilitating hydrogen adsorption and release progress. Experimental results indicate that the P-doped MoS 2 nanosheets with enlarged interlayer spacing exhibit remarkable electrocatalytic activity and good long-term operational stability (with Tafel slope of 34 mV/dec and an extremely low overpotential of ∼43 mV at 10 mA/cm 2 ) . Our method demonstrated a facile technology for improving the electrocatalytic efficiency of MoS 2 for hydrogen evolution reaction through nonmetal doping, which could be explored to enhance and understand the catalytic properties of other transition-metal chalcogenides.

Herein, the authors explicitly reveal the dual‐functions of N dopants in molybdenum disulfide (MoS2) catalyst through a combined experimental and first‐principles approach. The authors achieve an economical, ecofriendly, and most efficient MoS2‐based hydrogen evolution reaction (HER) catalyst of N‐doped MoS2 nanosheets, exhibiting an onset overpotential of 35 mV, an overpotential of 121 mV at 100 mA cm−2 and a Tafel slope of 41 mV dec−1. The dual‐functions of N dopants are (1) activating the HER catalytic activity of MoS2 S‐edge and (2) enhancing the conductivity of MoS2 basal plane to promote rapid charge transfer. Comprehensive electrochemical measurements prove that both the amount of active HER sites and the conductivity of N‐doped MoS2 increase as a result of doping N. Systematic first‐principles calculations identify the active HER sites in N‐doped MoS2 edges and also illustrate the conducting charges spreading over N‐doped basal plane induced by strong Mo 3d–S 2p–N 2p hybridizations at Fermi level. The experimental and theoretical research on the efficient HER catalysis of N‐doped MoS2 nanosheets possesses great potential for future sustainable hydrogen production via water electrolysis and will stimulate further development on nonmetal‐doped MoS2 systems to bring about novel high‐performance HER catalysts.

Atomically thin metallic Ni3N nanosheets fabricated as the hydrogen evolution cathode exhibit remarkable HER activity close to that of a commercial Pt/C electrode. The Ni atoms accompanied by surrounding N atoms on the N–Ni surface demonstrate a small ΔGH* of 0.065 eV due to the Ni–N co-effect, and thus act as the most active HER sites.

Here, N-doped cobalt pyrite (CoS 2 ) electrocatalytic material is developed via utilizing the synergic effect of N dopants and S vacancies. The catalyst displays high activity and stability for hydrogen evolution reaction. Density functional theory calculations and electrochemical characterizations reveal that the electrochemical activity of the CoS 2 catalyst is directly associated with the content of N dopants and S vacancies, where proper combinations of N dopants and S vacancies yield a minimized overpotential close to that of commercial Pt. What's more, optimized performance has been achieved by carefully manipulating the amounts of N dopants and S vacancies in N-doped CoS 2 catalyst, which exhibits a Tafel slope as small as 48 mV/dec, an ultralow overpotential of 57 mV at 10 mA/ cm 2 , and satisfying stability. This work highlights a feasible strategy to explore efficient electrocatalysts via nonmetal element doping and defect engineering.

Electrochemical water splitting to produce hydrogen and oxygen, as an important reaction for renewable energy storage, needs highly efficient and stable catalysts. Herein, FeS /CoS interface nanosheets (NSs) as efficient bifunctional electrocatalysts for overall water splitting are reported. The thickness and interface disordered structure with rich defects of FeS /CoS NSs are confirmed by atomic force microscopy and high-resolution transmission electron microscopy. Furthermore, extended X-ray absorption fine structure spectroscopy clarifies that FeS /CoS NSs with sulfur vacancies, which can further increase electrocatalytic performance. Benefiting from the interface nanosheets' structure with abundant defects, the FeS /CoS NSs show remarkable hydrogen evolution reaction (HER) performance with a low overpotential of 78.2 mV at 10 mA cm and a superior stability for 80 h in 1.0 m KOH, and an overpotential of 302 mV at 100 mA cm for the oxygen evolution reaction (OER). More importantly, the FeS /CoS NSs display excellent performance for overall water splitting with a voltage of 1.47 V to achieve current density of 10 mA cm and maintain the activity for at least 21 h. The present work highlights the importance of engineering interface nanosheets with rich defects based on transition metal dichalcogenides for boosting the HER and OER performance.

Low-coordination atoms (LCAs) have been proven to play a critical role in boosting electrocatalysis. However, for enhancing catalytic activity, suitably engineering the LCAs in catalysts through rational design remains a challenge. Herein, we demonstrated self-supporting NiO/Co 3 O 4 hybrids for advanced oxygen evolution reaction (OER) performance. Contributed to an abundance of heterointerfaces and increased oxygen vacancies at the interfaces, the numerous LCAs were generated in NiO/Co 3 O 4 . Consequently, the NiO/Co 3 O 4 heterostructures exhibited an overpotential of only 262 mV at 10 mA cm −2 and a low Tafel slope of 58 mV dec −1 . By employing density functional theory calculations, it was determined that the d electrons were effectively regulated. Moreover, the d-band centers of Co near the interface in NiO/Co 3 O 4 were far from the Fermi level, thereby confirming the reduction of the unfavorable strong adsorption to oxo intermediates during the OER process. This study provides an effective approach for the rational construction of hybrid interfaces.

As a large family of two-dimensional (2D) materials, transition metal dichalcogenides (TMDs) have been attracting an increasing level of attention and therefore considerable research input, owing to their intriguing catalytic, chemical and physical properties. The high exposed surface area, potentially large number of active sites, and chemical stability provide TMDs with vast opportunities for use as a unique class of electrocatalysts, while their low electrical conductivity and other deficiencies have drawn considerable research efforts for further modification. The optimization of TMDs can be achieved by several approaches, including site doping/modification, phase modulation, control of growth morphology and construction of heterostructures, by both appropriate computational simulations and purposely designed experimental studies. In tuning the TMD-based electrocatalysts, computational calculations have played uniquely important roles in predicting the structure and understanding the operational mechanism of catalytic performance. Indeed, the importance of refined calculations has been growing rapidly to provide comprehensive and unique guidance towards further modification of the existing TMD-based electrocatalysts and the discovery of new ones. In this critical review, we will look into the rapid advancement of the highly efficient TMD-based electrocatalysts that have been developed in recent years, achieved by combined computational and experimental approaches. Aiming to provide a generalized overall picture, we have conducted further computational studies as a systematic approach to unveil the modulation in the structure and the improvement in electrocatalytic properties brought in by appropriate element doping/modification in either basal plane A-(metal atoms) and B-(chalcogen atoms) sites or edge sites of the 2D TMD materials, as well as in some of those non-layered metal disulfides/diselenides. This review is concluded by summarizing the likely future development and perspectives of TMD-based electrocatalysts.

Hierarchical nanostructured architectures are demonstrated as an effective approach to develop highly active and bifunctional electrocatalysts, which are urgently required for efficient rechargeable metal-air batteries. Herein, a mesoporous hierarchical flake arrays (FAs) structure grown on flexible carbon cloth, integrated with the microsized nitrogen-doped carbon (N-doped C) FAs, nanoscaled P-doped CoSe 2 hollow clusters and atomiclevel P-doping (P-CoSe 2 /N-C FAs) is described. The P-CoSe 2 /N-C FAs thus developed exhibit a reduced overpotential (≈230 mV at 10 mA cm −2 ) toward oxygen evolution reaction (OER) and large half-wave potential (0.87 V) for oxygen reduction reactions. The excellent bifunctional electrocatalytic performance is ascribed to the synergy among the hierarchical flake arrays controlled at both micro-and nanoscales, and atomic-level P-doping. Density functional theory calculations confirm that the free energy for the potential-limiting step is reduced by P-doping for OER. An all-solid-state zinc-air battery made of the P-CoSe 2 /N-C FAs as the air-cathode presents excellent cycling stability and mechanical flexibility, demonstrating the great potential of the hierarchical P-CoSe 2 /N-C FAs for advanced bifunctional electrocatalysis.