Nitrate (NO₃⁻) contamination in water adversely affects human health and the ecosystem. Electrochemical methods can remediate environmental NO₃⁻ pollution. This study developed Ru-Cu₂O/Co₃O₄@copper foam (CF), a hierarchical catalyst comprising a CF substrate, Cu-Co layered double hydroxide (LDH) nanosheets, and ultrasmall Ru nanoparticles. Traditional characterization confirmed its active component composition and chemical oxidation states. Studies on electrochemical NO₃⁻ reduction have evaluated catalytic efficacy under various conditions. This catalyst exhibits exceptional efficacy in NO₃⁻ catalysis. At −1.61 V vs. Ag/AgCl, it converts 50 mg/L NO₃⁻–N into pure, environmentally friendly N₂ after 4 h, achieving a 98.44% removal efficiency and approximately 100% selectivity, enabling efficient NO₃⁻ elimination and green N conversion. Throughout 20 cycles, the removal rate of NO₃⁻–N remained consistently high (94.19%–99.53%), whereas N₂ selectivity exhibited excellent stability (93.62%–100%).

Nickel oxide (NiO_x) has emerged as a promising hole transport layer for perovskite light-emitting diodes (Pero-LEDs), yet its interfacial incompatibility with perovskite remains a critical challenge. The unmodified NiO_x surface typically exhibits a high density of defect states, including nickel vacancies, oxygen vacancies, and surface dangling bonds. Here, we develop an effective interface engineering strategy by using 3-guanidinopropionic acid (3-GPA), a structurally simple molecule featuring carboxyl and guanidine terminals. The carboxyl groups chemically anchor to NiO_x through coordination bonding, simultaneously passivating surface defects and optimizing surface energy barrier. Meanwhile, the guanidine groups interact synergistically with perovskite components through multiple coordination modes, significantly improving interfacial contact and crystallization quality. This dual-functional modification yields remarkable improvements: enhanced hole injection efficiency evidenced by increased current density, improved optoelectronic properties demonstrated by prolonged carrier lifetime, and superior interfacial stability confirmed under continuous illumination. The resulting devices achieve a peak external quantum efficiency of 25.25%, representing a 31.5% enhancement over control devices (19.20%). This work demonstrates a simple and effective buried interface modification strategy for high-performance NiO_x-based Pero-LEDs.

Hydrogen production by electrolysis of water is a key technology to achieve green hydrogen energy economy, but it relies on advanced catalyst materials with high efficiency, stability, and wide pH adaptability. In this study, Ni, Ru, and Pt ternary metals were embedded into nitrogen-doped hollow carbon spheres (NHCSs) by hydrothermal tandem heat treatment to form ternary supported metal nanoparticles with high dispersion and ultra-small particle size (~ 1.3 nm), which realized efficient hydrogen evolution from multi-scenario electrocatalytic water splitting. In the whole pH range, the performance of NiRuPt/NHCSs is better than that of commercial Pt/C catalyst, and the overpotentials under alkaline, neutral, and acidic conditions are as low as 15.5, 20.0, and 29.5 mV, respectively. Under industrial conditions, NiRuPt/NHCSs also have excellent hydrogen evolution reaction (HER) performance, achieving efficient electrolysis of seawater for hydrogen production, and achieving Ampere-level hydrogen production at low voltage (~ 1.76 V) on integrated membrane electrode assemblies. Density functional theory (DFT) calculations show that in the NiRuPt ternary metal, the Pt site is conducive to promoting the desorption of *H to form H₂, the Ru site is conducive to promoting the capture of H₂O, and the Ni site is conducive to promoting the dissociation of H₂O. Therefore, the formed NiRuPt ternary metal synergistically promotes multi-scenario efficient electrolysis of water to produce hydrogen. This study provides a new idea for the design of multi-component metal/carbon-based composite catalysts, and promotes the development of non-noble metal/noble metal composite catalysts in hydrogen production by electrolysis of water.

The electrolysis of water to produce hydrogen is an important technique to replace traditional fossil fuel-based hydrogen production. This method efficiently converts electrical energy into chemical energy, it is ostensibly a promising candidate for addressing the energy crisis. Significant effort has been devoted to developing efficient electrocatalysts for water electrolysis. The exploration of suitable catalytic materials for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and other bifunctional electrocatalytic reactions is crucial. Transition metal selenides (TMSes) have emerged as potential HER and OER electrocatalysts because of their unique electronic structures, which are beneficial for charge transfer, tuneable bandgaps, distinctive morphologies, and low-cost. This review discusses the mechanisms and performance comparisons of TMSes in overall water splitting under various pH conditions. From an industrial and commercial perspective, the catalytic performance of TMSes for the HER and OER is not ideal. Methods for preparing electrocatalytic materials and optimizing materials for overall water decomposition and modulation mechanisms have been introduced to improve electrocatalytic performance, such as element doping, carbon composites, bimetallic systems, morphology control, and heterogeneous interface engineering. Finally, the challenges and prospects of TMSes were discussed.