Electrochemical nitrate reduction reaction (NO₃RR) towards ammonia, as an emerging and appealing technology alternative to the energy-intensive Haber–Bosch process and inefficient nitrogen reduction reaction, has recently aroused wide concern and research. However, the current research of the NO₃RR towards ammonia lacks the overall performance comparison of various electrocatalysts. Given this, we here make a comparison of 12 common transition metal oxide catalysts for the NO₃RR under a high cathodic current density of 0.25 A·cm⁻², wherein Co₃O₄ catalyst displays the highest ammonia Faradaic efficiency (85.15%) and moderate activity (ca. −0.25 V vs. reversible hydrogen electrode). Other external factors, such as nitrate concentrations in the electrolyte and applied potential ranges, have also been specifically investigated for the NO₃RR.

Ni-based transition metal nitrides (TMNs) have been regarded as promising substitutes for noble-metal electrocatalysts towards the hydrogen evolution reaction (HER) due to their low cost, excellent chemical stability, high electronic conductivity, and unique electronic structure. However, facile green synthesis and rational microstructure design of Ni-based TMNs electrocatalysts with high HER activity remain challenging. In this work, we report the fabrication of Ni/Ni₃N heterostructure nanoarrays on carbon paper via a one-step magnetron sputtering method under low temperature and N₂ atmosphere. The Ni/Ni₃N hierarchical nanoarrays exhibit an excellent HER catalytic activity with a low overpotential of 37 mV at 10 mA·cm⁻² and robust long-term durability over 100 h. Furthermore, the Ni/Ni₃N||NiFeOH (NiFeOH = NiFe bimetallic hydroxide) electrolyzer requires a small voltage of 1.54 V to obtain 10 mA·cm⁻² for water electrolysis. Density functional theory (DFT) calculations reveal that the heterointerface between Ni and Ni₃N could directly induce electron redistribution to optimize the electronic structure, which accelerates the dissociation of water molecules and the subsequent hydrogen desorption, and thus boosting the HER kinetics.

Aqueous rechargeable Zn-ion batteries are regarded as a promising alternative to lithium-ion batteries owing to their high energy density, low cost, and high safety. However, their commercialization is severely restricted by the Zn dendrite formation and side reactions. Herein, we propose that these issues can be minimized by modifying the interfacial properties through introducing electrochemically inert Al₂O₃ nanocoatings on Zn meal anodes (Al₂O₃@Zn). The Al₂O₃ nanocoatings can effectively suppress both the dendrite growth and side reactions. As a result, the Al₂O₃@Zn symmetric cells show excellent electrochemical performance with a long lifespan of more than 4,000 h at 1 mA·cm⁻² and 1 mAh·cm⁻². Meanwhile, the assembled Al₂O₃@Zn//V₂O₅ full cells can deliver a high capacity (236.2 mAh·g⁻¹) and long lifespan with a capacity retention of 76.11% after 1,000 cycles at 4 A·g⁻¹.