As one of the most important chemicals and an energy carrier, synthetic ammonia has been widely studied to meet the increasing demand. Among various strategies, electrochemical nitrogen reduction reaction (e‐NRR) is a promising way because of its green nature and easy set‐up on large‐scale. However, its practical application is extremely limited because of the very‐low production rate, which is strongly dependent on the electrocatalysts used. Therefore, searching novel efficient electrocatalysts for e‐NRR is essential to promote the technology. In this review, it highlights the insights on the mechanism for the NH3 electrochemical synthesis, recommend a reliable protocol for the ammonia detection, and systematically summarize the recent development on novel electrocatalysts, including noble metal‐based materials, single‐metal‐atom catalysts, non‐noble metal, and their compounds, and metal‐free materials, for efficient e‐NRR in both experimental and theoretical studies. Various strategies to improve the catalytic performance by increasing exposed active sites or tuning electronic structures, including surface control, defect engineering, and hybridization, are carefully discussed. Finally, perspectives and challenges are outlined. It can be expected that this review provides insightful guidance on the development of advanced catalytic systems to produce ammonia through N2 reduction.

Ga2O3 photodetectors with interdigitated electrodes have been designed and fabricated, and the Ga2O3 area exposed to illumination acts as the active layer of the photodetector, while the area covered by Au interdigital electrode provide an arena for carrier multiplication. The photodetectors show a maximum responsivity at around 255 nm and a cutoff wavelength of 260 nm, which lies in the solar-blind region. The responsivity of the photodetector reaches 17 A/W when the bias voltage is 20 V, which corresponds to a quantum efficiency of 8228%, amongst the best value ever reported in Ga2O3 film based solar-blind photodetectors.

Ultraviolet photodetectors have been fabricated from n-ZnO/p-NiO core-shell nanowire arrays, the photodetectors can work without an external power source, and show a response only to a narrow spectrum region.Self-powered, highly spectrum-selective photodetectors have been fabricated from n-ZnO/p-NiO coreshell nanowire arrays. In the structure, the outer-layer of the p-NiO acts as a "filter" which can filter out the photons with short wavelength. In this way, highly spectrum-selective photodetectors that only respond to a narrow spectrum range have been obtained.

Although nitrogen-doped zinc oxide has been fabricated as a light-emitting diode, the origin of its p-type conductivity remains mysterious. Here, by analyzing the surface reaction pathway of N in ZnO with first-principles density functional theory calculations, we demonstrate that the origin of p-type conductivity of N-doped ZnO can originate from the defect complexes of N(Zn)-V(O) and N(O)-V(Zn). Favored by the Zn-polar growth, the shallow acceptor of N(O)-V(Zn) actually evolves from the double-donor state of N(Zn)-V(O). While N(Zn)-V(O) is metastable, the p-doping mechanism of N(Zn)-V(O)→N(O)-V(Zn) in ZnO will be free from the spontaneous compensation from the intrinsic donors. The results may offer clearer strategies for doping ZnO p-type more efficiently with N.