Guizhou University

Electrocatalytic nitrate reduction reaction (NO3RR) represents a sustainable and environmentally benign route for ammonia (NH3) synthesis. However, NO3RR is still limited by the competition from hydrogen evolution reaction (HER) and the high energy barrier in the hydrogenation step of nitrogen-containing intermediates. Here, we report a selective etching strategy to construct RuM nanoalloys (M = Fe, Co, Ni, Cu) uniformly dispersed on porous nitrogen-doped carbon substrates for efficient neutral NH3 electrosynthesis. Density functional theory calculations confirm that the synergic effect between Ru and transition metal M modulates the electronic structure of the alloy, significantly lowering the energy barrier for the conversion of *NO2 to *HNO2. Experimentally, the optimized RuFe-NC catalyst achieves 100% Faraday efficiency with a high yield rate of 0.83 mg h−1 mgcat−1 at a low potential of − 0.1 V vs. RHE, outperforming most reported catalysts. In situ spectroscopic analyses further demonstrate that the RuM-NC effectively promotes the hydrogenation of nitrogen intermediates while inhibiting the formation of hydrogen radicals, thereby reducing HER competition. The RuFe-NC assembled Zn-NO3− battery achieved a high open-circuit voltage and an outstanding power density and capacity, which drive selective NO3− conversion to NH3. This work provides a powerful synergistic design strategy for efficient NH3 electrosynthesis and a general framework for the development of advanced multi-component catalysts for sustainable nitrogen conversion.

WRKYs represent a large family of plant transcription factors characterized by a highly conserved WRKY domain. WRKY transcription factors are important for plant growth, development, and responses to environmental stresses. However, this family has not been previously identified in Sesuvium portulacastrum, a typical halophyte that grows in saline soils and coastal marshlands and contributes to the stability of coastal ecosystems. Here, we identified 68 SpWRKYs from S. portulacastrum and classified them into six subclades. These genes were unevenly distributed across twenty-two chromosomes and exhibited both intra- and interspecific expansion based on segmental duplication events, orthologous gene pairs, and duplication relationships. All SpWRKY proteins contained at least one conserved WRKY domain, and their promoters contain 33 cis-elements involving abiotic stress signaling, developmental regulation, phytohormone responses, light responsiveness, and tissue-specific expression. Transcriptome analysis under cadmium, copper, and salt stress showed that many SpWRKYs were stress-responsive. Among them, SpWRKY40 and SpWRKY51 showed 3.8-fold and 4.2-fold induction in roots under cadmium treatment, which was further confirmed by quantitative real-time PCR. Subcellular localization and transient expression in tobacco, together with yeast one-hybrid experiments, demonstrated that SpWRKY40 and SpWRKY51 function as transcription activators. They bind specifically to the GTCAA and TTGACC cis-elements. Our study provides a detailed overview of the SpWRKY family and functional insights into SpWRKY40 and SpWRKY51 as transcription activators. The findings offer valuable candidate genes for future applications in improving cadmium stress tolerance in S. portulacastrum and related crop species.

The siroheme-containing nitrite reductase (NirBD), which is encoded by the nirBD gene, is a functional enzyme in the nitrogen cycle. The NirBD enzyme can regulate N₂O release through the two distinct pathways of assimilatory nitrate/nitrite reduction to biomass and dissimilatory nitrate/nitrite reduction to ammonium. Therefore, a thorough comprehension of the function of NirBD in microorganisms can enable us to better understanding the contributions for nitrogen retention and N₂O emission. However, the knowledge of the functions and expression mechanisms of nirBD gene across different microorganisms remains limited. This review synthesized the current research on the phylogenetic distribution and catalytic versatility of NirBD in fungi, bacteria, and actinomycetes. The contributions of NirBD for nitrogen retention and N₂O emission were extensively discussed under anaerobic and aerobic conditions. The expression mechanism of NirBD was demonstrated. The factors that affect the expression amount of the NirBD enzyme in microorganisms were clarified systematically. This review not only elucidated the unique role of NirBD in the nitrogen metabolism but also provided a critical theoretical foundation for developing future strategies to enhance soil nitrogen fertility and mitigate N₂O emissions.