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The search for effective electrocatalysts for energy conversion is crucial for the advancement of green energy. Electrodeposition is a simple but effective method of preparing improved electrodes for use in the electrochemical sector. In the present work, we have synthesized amorphous NiMoSe nanospheres on Ni foam (NF) via a simple electrodeposition method. The synthesized NiMoSe demonstrates outstanding catalytic activity for the hydrogen evolution reaction (HER), with a small overpotential of 130 mV at a current density of 10 mA cm−2 in 1 M KOH electrolyte and a small Tafel slope of 59 mV dec−1. Furthermore, NiMoSe also shows long-term durability over 45 h. ; This work was supported by the Human Resources Development Program (No. 20194030202470) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) Grant funded by the Korean Government Ministry of Trade, Industry and Energy. This work was supported by the Technology Development Program to Solve Climate Changes of the National Research Foundation (grant no. 2016M1A2A2936784) funded by the Ministry of Science and ICT.

AbstractAmmonia serves as an irreplaceable raw material for nitrogen fertilizers, which is essential for global food production. In addition, it has been recently endowed with a new function as a carrier of renewable energy, demonstrating significant research prospects. However, the highly developed ammonia industry results in abundant nitrogenous wastes in nature, thus causing severe nitrogen pollution and disrupting the global nitrogen cycle. The environmentally friendly electrocatalytic technologies for upcycling nitrogenous wastes to green ammonia represent a highly valuable transformation strategy. In this review, we present three effective pathways for the electrocatalytic reduction of nitrogenous wastes to green ammonia, including nitrate reduction reaction (NO3RR), nitrite reduction reaction (NO2RR), and nitric oxide reduction reaction (NORR). Furthermore, achievements and challenges associated with electrocatalysts for green ammonia synthesis are discussed in terms of noble metal-based electrocatalysts, non-noble metal-based electrocatalysts, and metal-free electrocatalysts. Moreover, this review provides a systematic perspective on reaction mechanisms, catalyst design, and future developments, offering new insights and prospects for the value-upgrading cycle of nitrogenous substances. By exploring the potential of green ammonia synthesis, we aim to contribute to the development of sustainable and environmentally friendly ammonia production.

The project Nr. AP05131211 "First Principles Investigation on Catalytic Properties of N-doped Co3O4" is supported by the Ministry of Education and Science of the Republic of Kazakhstan within the framework of the grant funding for scientific and (or) scientific and technical research for 2018-2020. The authors thank T. Inerbaev and A. Popov for fruitful discussions and valuable suggestions. Yu.M. thanks M.Putnina for the technical assistance in preparation of the manuscript. ; N-doped Co3O4 is a promising electrocatalyst. By means of first-principles calculations, various concentrations and spatial arrangements of NO atoms were modelled. Mutual interaction of the dopant atoms was analysed with respect to single NO atom. Charge redistribution, caused by doping, was calculated. ; Ministry of Education and Science of the Republic of Kazakhstan No. AP05131211; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²

The hydrogen evolution reaction (HER) is a key process in electrochemical water splitting. To lower the cost and environmental impact of this process, it is highly motivated to develop electrocatalysts with low or no content of noble metals. Here, we report on an ingenious synthesis of hybrid PtxNi1-x electrocatalysts in the form of a nanoparticle-nanonetwork structure with very low noble metal content. The structure possesses important features such as good electrical conductivity, high surface area, strong interlinking, and substrate adhesion, which render an excellent HER activity. Specifically, the best performing Pt0.05Ni0.95 sample demonstrates a Tafel slope of 30 mV dec-1 in 0.5 M H2SO4 and an overpotential of 20 mV at a current density of 10 mA cm-2 with high stability. The impressive catalytic performance is further rationalized in a theoretical study, which provides insight into the mechanism on how such small platinum content can allow for close-to-optimal adsorption energies for hydrogen. ; Funding Agencies|Vetenskapsraodet [2017-04862, 2017-04380]; Energimyndigheten [45419-1, 50779-1]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO Mat LiU) [2009 00971]