Longcheng Zhang

Electrochemical nitrate reduction to ammonia couples nitrogen‐pollutant remediation with sustainable ammonia synthesis, yet its complex interfacial reaction network remains difficult to resolve. In situ Raman spectroscopy provides access to aqueous interfacial chemistry, adsorbed NO _x species, dynamic catalyst phases, and local microenvironments under operating conditions. However, many studies still rely mainly on peak assignment, even though the mechanistic reliability of individual spectral features varies substantially. This Perspective presents a Raman‐centered diagnostic framework for nitrate electroreduction. Raman signals are organized into four interfacial readouts: adsorbed nitrate and nitrite species, hydrogenated nitrogen intermediates, catalyst reconstruction, and interfacial water and ion structures. An evidence hierarchy is introduced to assess Raman assignments through isotope labeling, potential‐, time‐, and space‐resolved measurements, multimodal validation, and quantitative correlations with product distributions. Emerging opportunities in evidence‐ranked spectral atlases, interpretable data‐driven analysis, and online Raman monitoring are also discussed. By moving beyond isolated spectral fingerprints, in situ Raman spectroscopy serves as a dynamic interfacial probe for understanding, comparing, and ultimately controlling nitrate electroreduction.

Direct seawater electrolysis at industrially relevant current densities is constrained by chloride adsorption, competing chlorine oxidation, and accelerated anode corrosion. Here, we identify interfacial stannate formed during anodic operation as a key species responsible for suppressing Cl– adsorption and competing chlorine evolution. Operando Raman spectroscopy, inductively coupled plasma mass spectrometry, and time-of-flight secondary ion mass spectrometry reveal the partial dissolution of incorporated Sn species and the enrichment of stannate at the reconstructed catalyst–electrolyte interface, while density functional theory calculations further support its role in weakening Cl– adsorption. The resulting Sn-containing NiFe anode requires an overpotential of 377 mV to reach 1 A cm–2 and sustains operation at 1 and 2 A cm–2 for 1500 and 850 h, respectively. An anion-exchange-membrane electrolyzer further delivers 1 and 4 A cm–2 at cell voltages of 1.90 and 2.54 V at 80 °C, operates continuously for 1000 h at 1 A cm–2, and withstands 4500 start–shutdown cycles over 250 h. These results establish a direct link between working-state stannate chemistry and long-term chloride resistance under ampere-level seawater electrolysis.

Developing industrial-grade alkaline hydrogen evolution catalysts remains a critical challenge due to sluggish water dissociation and limited proton availability at the electrode–electrolyte interface. Here, we construct a metastable Ni/Ni3C core–shell structure and anchor atomically dispersed Ru single-atom sites (Ru SAs/Ni@Ni3C) to overcome this bottleneck. In situ studies reveal that Ru sites selectively adsorb hydroxyl species, enabling a dynamic OH– spillover that rapidly refreshes adjacent Ni active sites. Concurrently, an optimized interfacial water network accelerates proton transport. This synergy between Ru single atoms and the non-equilibrium core–shell substrate achieves exceptional activity and stability through a cooperative hydrogen adsorption–desorption cycle. Ru SAs/Ni@Ni3C demonstrated stable operation at 2 A cm–2 for more than 600 h in an anion-exchange-membrane water electrolyzer (AEMWE). These findings establish a generalizable strategy for designing efficient and durable electrocatalysts for alkaline water electrolysis.

The rapid expansion of electrocatalysis research has driven extensive reporting of new materials for water splitting, fuel cells, carbon dioxide reduction, and other electrochemical reactions. However, the widespread use of linear-sweep voltammetry (LSV) as the primary indicator of catalytic activity can obscure the reliability and reproducibility of electrocatalyst evaluation. As a single-sweep polarization measurement, LSV records only an apparent current–potential response along a selected scan path and offers limited insight into whether the measured current reflects a reproducible catalytic response or transient interfacial processes. Cyclic voltammetry (CV), by contrast, provides a more informative framework by incorporating forward and reverse scans, repeated cycling, and scan-history-dependent responses. These features allow CV to reveal surface redox behavior, adsorption/desorption processes, hysteresis, catalyst activation or reconstruction, and the reproducibility of the electrochemical response. However, the role of CV as a state-validation and interfacial diagnostic tool remains underutilized in contemporary electrocatalysis research. This perspective revisits the fundamental differences between CV and LSV, highlights why LSV is insufficient as a standalone method for assessing catalytic activity, and argues that CV-based state validation should complement LSV-based activity comparison. Practical recommendations are further provided to improve the reliability, reproducibility, and comparability of electrocatalytic benchmarking.

A central challenge in single-atom catalysis lies in the precise construction of structurally well-defined local coordination environments at isolated metal sites while retaining low coordination numbers. Here, we present an edge-bonding strategy that confines isolated metal atoms to well-defined edge sites of covalent triazine frameworks, enabling deterministic construction of structurally defined low-coordination environments. With Ni as a model, this approach yields single-atom sites with a well-defined Ni-N₁-C₆ coordination motif and allows precise control over their spatial distribution. The strategy is readily extendable to other metals, affording single-atom catalysts with structurally defined and highly accessible low-coordination environments. Such geometrically low-coordination sites optimize photogenerated carrier separation and transport while selectively stabilizing the key *OCHO intermediate in the CO₂ reduction pathway, thereby directing the reaction toward HCOOH with 98.5% selectivity. This work establishes a principle for achieving low-coordination microenvironments at single-atom sites via macroscopic regulation of support structures, providing a rational strategy for single-atom catalyst design.

Anodic activation creates a specific CoFe-(oxy)hydroxide interface on spinel CoFe _0.25 Cr _1.75 O ₄ , enabling spontaneous lattice-proton supply for fast nitrate hydrogenation and broad-window ammonia electrosynthesis.

Manipulating the selectivity-determining step in the hydrogenation of nitrogen-containing intermediates is critical to achieving high ammonia selectivity in electrocatalytic nitrate reduction. Here, we propose a molecular interface engineering strategy that functionalized with thiol-anchored aromatic ligands to regulate the interfacial binding affinity and activation of key nitrogen-containing intermediates on silver nanocube surfaces. By systematically varying the electronic properties of the substituents, we identify 4-(methylthio)benzaldehyde as the most effective ligand, increasing the ammonia Faradaic efficiency from 50.8% to 98.9% and achieving a yield rate of 14,366.1 μg h^–1 cm_geo^–2 at –0.63 V versus reversible hydrogen electrode. In situ electrochemical characterizations combined with theoretical simulations further reveal that 4-(methylthio)benzaldehyde modification promotes the activation of weakly hydrogen-bonded water molecules and accelerates the hydrogenation of *HNO intermediates. This targeted modulation of interfacial binding affinity offers an effective strategy for selectivity control in electrocatalytic nitrate reduction. The enhanced performance is further validated in a membrane electrode assembly electrolyser, underscoring the practical viability of this molecular design strategy for selective nitrate conversion.