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The metallic (1T) transition metal dichalcogenides (TMDCs) are known for their superior electrocatalytic performance, due to their high conductivity, active basal-planes, and exposed edges. Our novel approach of coupling a metallic-NiTe2/Ni nano-skeleton with 1T-Co-WS2nanosheet in a core–shell arrangement to develop a hybrid heterostructure (1T Co-WS2/NiTe2/Ni) has helped to outperform the trifunctional-electrocatalytic activity (HER, OER, and ORR). 1T-Co-WS2/NiTe2/Ni only requires ultralow overpotential (ηHER= 88 mV@10, ηOER= 290 mV@30), higher half-wave potential for ORR (E1/2= 0.781 V vs RHE), small Tafel slopes (HER = 68 mV dec-1, OER = 98 mV dec-1, and ORR = 63 mV dec-1) with high electrocatalytic surface area and robust stability in corresponding half-cell reactions. The designed heterostructured electrocatalyst (1T Co-WS2/NiTe2/Ni) presented exceptional total water-splitting performance, requiring a low voltage of 1.521 V to yield 10 mA cm−2current with extensive structural and electrochemical durability. Such performance could be attributed towards improved nanochannel morphology with exposed active edge, fluent electrode-kinetics, facile adsorption–desorption of reaction intermediates owing to the intrinsically tuned 1T-WS2by cobalt-doping, and hybridized NiTe2/Ni nano-skeleton. The DFT study confirmed that the incorporation of Co atoms in basal plane and the edge sites of WS2lattice induces the redistribution and modulation of electronic structure for fast electron/charge transfer and the synergistic coupling of 1T NiTe2heterostructures bolstered the electrocatalytic activity of the as-prepared catalysts. These outcomes provide a prospect towards the design and application of efficient 2D/2D heterostructured electrocatalyst for zero emission energy goal.

The production and handling of hydrogen (H2) energy has recently been recognized as being one of the most important technology issues to achieve a sustainable H2economy in the future. Different NH3-to-H2conversion technologies and especially ammonia electrooxidation reaction (AER) have been considered an effective mean for high-performance H2energy application alongside the progress of water electrolysis approach. Since AER at low temperature (<100 °C) causes sluggish kinetics, the reaction efficiency seriously depends on cost of electric source and catalytic efficiency. Therefore, various engineering approaches to design nanocatalysts with the unique modification of surface chemistry, electronic structure, electroactive sites, and conductivity have emerged to enhance their activity and stability towards AER. The AER kinetics and mechanism on nanocatalyst surface were also investigated to further understand issues associated with this technology during H2production, and then to find sufficient candidates for effective commercialization. Herein, we provided a summary of recent advanced NH3-to-H2technologies together with a comprehensive review of nanocatalyst development towards H2production via AER. Pros and cons of nanocatalysts, along with their promising commercialization future were also discussed in detail. The review is expected to offer useful knowledge to accelerate future research into this potential technology.

To meet the demands of the future green energy industry, there is a need for the cost-effective development of high-efficient electrocatalysts with optimal durability for water splitting and Zn-air batteries. In this work, a novel multifunctional electrocatalyst based on ultrafine Au@Co2N0.67core/shell nanodots interspersed 3D-NGr (Au@Co2N0.67/3D-NGr) with extraordinary activity and durability toward the hydrogen evolution reaction, oxygen evolution reaction, and oxygen reduction reaction has been developed that tends to show similar activity to the benchmark Pt/C and RuO2/C catalysts. Significantly, the Au@Co2N0.67/3D-NGr hybrid shows excellent overall water splitting potential while requiring small cell voltages of 1.58 and 1.79V to achieve 10 and 50mAcm-2, respectively. In addition, Zn-air batteries using the developed Au@Co2N0.67/3D-NGr hybrid demonstrate high performance, an expected open circuit potential of 1.46V, a large power density of 142.8mWcm-2, good rechargeability, and a high cycling life.

Heteroatom doping engineering has emerged as an intriguing strategy to enhance electrocatalytic efficiency. Herein, a multiple transition metal doping approach is developed through the incorporation of both Co and Nb into hierarchical MoS2ultrathin nanosheets directly grown on micro-TiO2hollow spheres (Co,Nb-MoS2/TiO2HSs) to boost the hydrogen evolution (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). The Co and Nb dual-doping effects modify the electronic structure of the host MoS2towards maximizing the HER, OER, and ORR performance. Additionally, the unique hollow spherical structure and heterostructured synergistic effects between the TiO2core and MoS2shell provide effective channels for electron transfer and large surface activity with abundant exposed void spaces for ion diffusion/penetration. Therefore, the Co,Nb-MoS2/TiO2HSs catalyst demonstrates extraordinary activity and stability with small overpotentials of 58.8 and 260.0mV at 10mAcm-2for the HER and OER, respectively. When employed as both cathodic and anodic electrode in an electrolyzer, the catalyst requires an operating voltage of 1.57V to achieve 10mAcm-2. The catalyst also exhibits great potential for the ORR with high onset potential of 0.96V and half-wave potential of 0.87V, as well as direct four-electron transfer process.