Asymmetric diatomic catalysts (ADCs) represent a promising class of sustainable electrocatalysts, featuring exceptional atom efficiency and dual active sites with asymmetric coordination environments. The asymmetric charge distribution in ADCs generates a local built-in electric field, enhancing charge separation/transfer and facilitating synergistic multi-step catalysis. This inherent structural complexity boosts catalytic performance by modulating the adsorption orientation and electronic configuration of intermediates. Importantly, the establishment of precise structure-activity correlations and the elucidation of underlying reaction mechanisms are of critical significance. This review provides a comprehensive overview of recent advancements in ADCs, with particular emphasis on classification methodologies, the application of artificial intelligence (AI), advanced characterization techniques, and their applications in key electrocatalytic reactions, such as oxygen reduction (ORR), oxygen evolution (OER), hydrogen evolution (HER), and carbon dioxide reduction (CO₂RR). Finally, the unresolved challenges and proposes potential research directions to advance the implementation of ADCs in energy systems are discussed.

Rechargeable aqueous Zn-I₂ batteries face challenges from zinc anode degradation (dendrites, corrosion) and polyiodide (I₃^-/I₅^-) shuttling at the cathode, limiting cycle life. To address these issues simultaneously, a novel an ion-selective, solvation-regulating, and flexible sulfonic acid-based water reducer gel electrolyte (PAM-FDN-CCS/ZSO) is designed in this work. This electrolyte features a 3D porous structure and abundant polar groups enabling efficient Zn²⁺ transport and solvation structure regulation, promoting uniform zinc deposition and suppressing water-related side reactions (e.g., hydrogen evolution) at the anode. Crucially, the strongly negatively charged sulfonic acid groups impart exceptional ion selectivity: they electrostatically repel polyiodide anion, effectively blocking their shuttle to the anode and minimizing active iodine loss, while permitting unimpeded Zn²⁺ diffusion. Consequently, Zn-I₂ full cells employing this multifunctional gel electrolyte achieve outstanding cycling stability, retaining 118.5 mAh g^-1 after 9,000 cycles at 5 A g^-1. This work achieves the synergistic optimization of interface issues in Zn-I₂ batteries by constructing an ion-selective multifunctional gel electrolyte, significantly enhancing their overall electrochemical performance.

Developing high-performance catalysts suitable for a wide pH range in catalytic ozonation system remains a significant challenge, primarily owing to the limitations imposed by metal species and the pH at the point of zero charge. In this study, an O doped g-C₃N₄/CuO (CNO-CuO) catalyst was synthesized via a facile method. Compared to pristine g-C₃N₄/CuO (CN-CuO), CNO-CuO dramatically enhanced the degradation efficiency of pollutants from 25% to 100% in acidic solutions. Moreover, it exhibited the efficient degradation efficiencies across a broad pH range (3–10), demonstrating that introduction of O atoms considerably improved the universality of CNO-CuO. Experimental and theoretical studies revealed that the synergistic interaction between CuO and C–O bonds was responsible for the remarkable catalytic ozonation activity over a wide pH range. Crucially, the incorporation of O atoms contributed to reversible formation of Cu⁺, ensuring the continuous regeneration of active sites and the sustained formation of ·OH. Additionally, the C–O bond acted as a potential catalytic active site, further enhancing treatment efficiency as pH increased. This work provided a feasible strategy for broadening catalyst applicability in catalytic ozonation systems through heteroatom doping.

Electrocatalytic nitrate reduction (NO₃RR) offers a promising route for sustainable ammonia synthesis and wastewater treatment, yet designing highly active and selective catalysts remains challenging. Herein, we construct an N-bridge anchored asymmetric AgCu dual-atomic catalyst on Ti₃C₂T_x MXene (AgCu DAC/Ti₃C₂T_x) for efficient nitrate electroreduction. The unique N-bridged structure stabilizes the asymmetric AgCu dual sites, enabling synergistic adsorption and activation of nitrate intermediates. In situ X-ray absorption fine structure (XAFS) spectroscopy confirms the dynamic evolution of the Ag-Cu coordination under reaction conditions, revealing their maintained heteronuclear pairing and electronic coupling during NO₃RR. As a result, the AgCu DAC/ Ti₃C₂T_x catalyst achieves a high NH₃ Faradaic efficiency of ~97.1% with an exceptional yield rate of ~3.1 mg h^-1 cm^-2 at −0.5 V vs. RHE, surpassing most reported dual-atom catalysts. This work provides insights into the design of asymmetric dual-atomic sites for multi-step catalytic reactions.

Electrochemical CO₂ reduction reaction (CO₂RR) into high-value chemicals and fuels is recognized as a promising strategy for mitigating energy and environmental challenges. However, this process frequently faces limitations due to inadequate selectivity towards specific products and insufficient electrochemical stability. Main group indium (In) catalysts have emerged as promising materials for CO₂RR to highly valued formate. In this study, we constructed an indium cluster material with charge-asymmetric atomic structure anchored on nitrogen-free carbon nanoframeworks (designated as In Clu/C), which exhibits exceptional efficiency as a CO₂RR catalyst for formate production. Notably, the In Clu/C achieves a remarkable formate Faradaic efficiency of 98.7% at −0.70 V. Furthermore, in-situ X-ray absorption spectroscopy (XAS) measurements reveal that the superior catalytic performance can be attributed to partially positively charged In^δ+ (0 < δ < 3) active sites. This discovery may provide new insights into the precise synthesis of metal cluster catalysts for environmental and energy applications.

Designing catalysts with highly active, selectivity, and stability for electrocatalytic CO₂ to formate is currently a severe challenge. Herein, we developed an electronic structure engineering on carbon nano frameworks embedded with nitrogen and sulfur asymmetrically dual-coordinated indium active sites toward the efficient electrocatalytic CO₂ reduction reaction. As expected, atomically dispersed In-based catalysts with In-S₁N₃ atomic interface with asymmetrically coordinated exhibited high efficiency for CO₂ reduction reaction (CO₂RR) to formate. It achieved a maximum Faradaic efficiency (FE) of 94.3% towards formate generation at −0.8 V vs. reversible hydrogen electrode (RHE), outperforming that of catalysts with In-S₂N₂ and In-N₄ atomic interface. And at a potential of −1.10 V vs. RHE, In-S₁N₃ achieves an impressive Faradaic efficiency of 93.7% in flow cell. The catalytic performance of In-S₁N₃ sites was confirmed to be enhanced through in-situ X-ray absorption near-edge structure (XANES) measurements under electrochemical conditions. Our discovery provides the guidance for performance regulation of main group metal catalysts toward CO₂RR at atomic scale.