Electrocatalytic nitrate reduction reaction (NO₃RR) offers a unique rationale for green NH₃ synthesis, yet the lack of high-efficiency NO₃RR catalysts remains a great challenge. In this work, we show that Au nanoclusters anchored on TiO₂ nanosheets can efficiently catalyze the conversion of NO₃RR-to-NH₃ under ambient conditions, achieving a maximal Faradic efficiency of 91%, a peak yield rate of 1923 μg·h⁻¹·mg_cat.⁻¹, and high durability over 10 consecutive cycles, all of which are comparable to the recently reported metrics (including transition metal and noble metal-based catalysts) and exceed those of pristine TiO₂. Moreover, a galvanic Zn-nitrate battery using the catalyst as the cathode was proposed, which shows a power density of 3.62 mW·cm⁻² and a yield rate of 452 μg·h⁻¹·mg_cat.⁻¹. Theoretical simulations further indicate that the atomically dispersed Au clusters can promote the adsorption and activation of NO₃⁻ species, and reduce the NO₃RR-to-NH₃ barrier, thus leading to an accelerated cathodic reaction. This work highlights the importance of metal clusters for the NH₃ electrosynthesis and nitrate removal.

As an ideal carbon-free energy carrier, ammonia plays an indispensable role in modern society. The conventional industrial synthesis of NH₃ by the Haber–Bosch technique under harsh reaction conditions results in serious energy consumption and environmental pollution. Therefore, it is essential to develop NH₃ synthesis tactics under benign conditions. Electrochemical synthesis of NH₃ has the advantages of mild reaction conditions and environmental friendliness, and has become a hotspot for research in recent years. It has been reported that zinc-nitrogen batteries (ZNBs), such as Zn-N₂, Zn-NO, Zn-NO₃⁻, and Zn-NO₂⁻ batteries, can not only reduce nitrogenous species to ammonia but also have concomitant power output. However, the common drawbacks of these battery systems are unsatisfactory power density and ammonia production. In this review, the latest progress of ZNBs including the reaction mechanism of the battery and reactor design principles is systematically summarized. Subsequently, active site engineering of cathode catalysts is discussed, including vacancy defects, chemical doping, and heterostructure engineering. Finally, some insights are provided to improve the performance of ZNBs from a practical perspective of view.

Facilitated by reactive oxygen species (ROS)-involved therapies, tumor cells undergo immunogenic cell death (ICD) to stimulate long-term immunity response. However, it is hard to trigger abundant and large-scale ICD for satisfactory cancer immunotherapy. Herein, a multifunctional sonosensitizer that consists of Au single atoms and clusters anchored on TiO₂ nanosheets (named Au_S/C-TiO₂) is reported for augmented sonodynamic therapy (SDT) and glucose depletion, which ultimately induce robust ICD due to the improved ROS generation and strong endoplasmic reticulum (ER) stress. The synergy effect between Au cluster/single atom with TiO₂ nanosheets intensifies apoptosis and ICD pathways to inhibit 80% of tumor cells through in vivo analyses. Furthermore, immune cells in vivo analyses verify the effectiveness of Au_S/C-TiO₂ sonosensitizer towards the induction of antitumor immunity. This study thus reveals that simultaneous presence of ROS generation and strong ER stress can efficiently evoke a strong ICD-mediated immune response.

Aqueous rechargeable Zn–gas batteries are regarded as promising energy storage and conversion devices due to their high safety and inherent environmental friendliness. However, the energy efficiency and power density of Zn–gas batteries are restricted by the kinetically sluggish cathode reactions, such as oxygen evolution reaction (OER) during charging and oxygen reduction reaction (ORR)/carbon dioxide reduction reaction (CO₂RR)/nitrogen reduction reaction (NRR)/nitric oxide reduction reaction (NORR) during discharge. In this review, battery configurations and fundamental reactions in Zn–gas batteries are first introduced, including Zn–air, Zn-CO₂, Zn-N₂, and Zn-NO batteries. Afterward, recent advances in active site engineering for enhancing the intrinsic catalytic activities of cathode catalysts are summarized. Subsequently, the structure and surface regulation strategies of cathode materials for optimizing the three-phase interface and improving the performance of Zn–gas batteries are discussed. Finally, some personal perspectives for the future development of Zn–gas batteries are presented.

Electrochemical nitric oxide reduction reaction (NORR) to produce ammonia (NH₃) under ambient conditions is a promising alternative to the energy and carbon-intensive Haber–Bosch approach, but its performance is still improved. Herein, molybdenum carbides (MoC) nanocrystals confined by nitrogen-doped carbon nanosheets are first designed as an efficient and durable electrocatalyst for catalyzing the reduction of NO to NH₃ with maximal Faradaic efficiency of 89% ± 2% and a yield rate of 1,350 ± 15 μg·h⁻¹·cm⁻² at the applied potential of −0.8 V vs. reversible hydrogen electrode (RHE) as well as high stable activity with negligible current density and NH₃ yield rate decays over a 30 h continue the test. Moreover, as a proof-of-concept of Zn–NO battery, it achieves a peak power density of 1.8 mW·cm⁻² and a large NH₃ yield rate of 782 ± 10 μg·h⁻¹·cm⁻², which are comparable to the best-reported results. Theoretical calculations reveal that the MoC(111) has a strong electronic interaction with NO molecules and thus lowering the energy barrier of the potential-determining step and suppressing hydrogen evolution kinetics. This work suggests that Mo-based materials are a powerful platform providing great opportunities to explore highly selective and active catalysts for NH₃ production.

Electrocatalytic NO reduction reaction to generate NH₃ under ambient conditions offers an attractive alternative to the energy-extensive Haber–Bosch route; however, the challenge still lies in the development of cost-effective and high-performance electrocatalysts. Herein, nanoporous VN film is first designed as a highly selective and stable electrocatalyst for catalyzing reduction of NO to NH₃ with a maximal Faradaic efficiency of 85% and a peak yield rate of 1.05 × 10^–7 mol·cm^–2·s^–1 (corresponding to 5,140.8 μg·h^–1·mg_cat.^–1) at –0.6 V vs. reversible hydrogen electrode in acid medium. Meanwhile, this catalyst maintains an excellent activity with negligible current density and NH₃ yield rate decays over 40 h. Moreover, as a proof-of-concept of Zn–NO battery, it delivers a high power density of 2.0 mW·cm^–2 and a large NH₃ yield rate of 0.22 × 10^–7 mol·cm^–2·s^–1 (corresponding to 1,077.1 μg·h^–1·mg_cat.^–1), both of which are comparable to the best-reported results. Theoretical analyses confirm that the VN surface favors the activation and hydrogenation of NO by suppressing the hydrogen evolution. This work highlights that the electrochemical NO reduction is an eco-friendly and energy-efficient strategy to produce NH₃.

The electrosynthesis of hydrogen peroxide (H₂O₂) from oxygen reduction reaction (ORR) via a two-electron pathway provides an appealing alternative to the energy-intensive anthraquinone route; however, the development of ORR with high selectivity and durability for H₂O₂ production is still challenging. Herein, we demonstrate an active and stable catalyst, composing of highly dispersed Ag nanoclusters on N-doped hollow carbon spheres (NC-Ag/NHCS), which can effectively reduce O₂ molecules into H₂O₂ with a selectivity of 89%–91% in a potential range from 0.2 to 0.7 V (vs. reversible hydrogen electrode (RHE)) in acidic media. Strikingly, NC-Ag/NHCS achieve a mass activity of 27.1 A·g⁻¹ and a yield rate of 408 mmol·g_cat.⁻¹·h⁻¹ at 0.7 V, both of which are comparable with the best-reported results. Furthermore, NC-Ag/NHCS enable catalyzing H₂O₂ production with a stable current density over 48-h electrolysis and only about 9.8% loss in selectivity after 10,000 cycles. Theoretical analyses indicate that Ag nanoclusters can contribute more electrons to favor the protonation of adsorbed O₂, thus leading to a high H₂O₂ selectivity. This work confirms the great potential of metal nanocluster-based materials for H₂O₂ electrosynthesis under ambient conditions.

An effective electrocatalyst being highly active in all pH range for oxygen reduction reaction (ORR) is crucial for energy conversion and storage devices. However, most of the high-efficiency ORR catalysis was reported in alkaline conditions. Herein, we demonstrated the preparation of atomically dispersed Fe-Zn pairs anchored on porous N-doped carbon frameworks (Fe-Zn-SA/NC), which works efficiently as ORR catalyst in the whole pH range. It achieves high half-wave potentials of 0.78, 0.85 and 0.72 V in 0.1 M HClO₄, 0.1 M KOH and 0.1 M phosphate buffer saline (PBS) solutions, respectively, as well as respectable stability. The performances are even comparable to Pt/C. Furthermore, when assembled into a Zn-air battery, the high power density of 167.2 mW·cm^-2 and 120 h durability reveal the feasibility of Fe-Zn-SA/NC in real energy-related devices. Theoretical calculations demonstrate that the superior catalytic activity of Fe-Zn-SA/NC can be contributed to the lower energy barriers of ORR at the Fe-Zn-N₆ centers. This work demonstrates the potential of Fe-Zn pairs as alternatives to the Pt catalysts for efficient catalytic ORR and provides new insights of dual-atom catalysts for other energy conversion related catalytic reactions.

Catalytic oxidation of toluene over noble metal catalysts is a representative reaction for elimination of volatile organic compounds (VOCs). However, to fully understand the activation of molecular oxygen and the role of active oxygen species generated in this reaction is still a challenging target. Herein, MgO nanosheets and single-atom Pt loaded MgO (Pt SA/MgO) nanosheets were synthesized and used as catalysts in toluene oxidation. The activation process of molecular oxygen and oxidation performance on the two catalysts were contrastively investigated. The Pt SA/MgO exhibited significantly enhanced catalytic activity compared to MgO. The oxygen vacancies can be easily generated on the Pt SA/MgO surface, which facilitate the activation of molecular oxygen and the formation of active oxygen species. Based on the experimental data and theoretical calculations, an active oxygen species promoted oxidation mechanism for toluene was proposed. In the presence of H₂O, the molecular oxygen is more favorable to be dissociated to generate ^•OH on the oxygen vacancies of the Pt SA/MgO surface, which is the dominant active oxygen species. We anticipate that this work may shed light on further investigation of the oxidation mechanism of toluene and other VOCs over noble metal catalysts.

Natural organisms contain rich elements and naturally optimized smart structures, both of which have inspired various innovative concepts and designs in human society. In particular, several natural organisms have been used as element sources to synthesize low-cost and environmentally friendly electrocatalysts for the oxygen reduction reaction (ORR) in fuel cells and metal-air batteries, which are clean energy devices. However, to date, no naturally optimized smart structures have been employed in the synthesis of ORR catalysts, including graphene-based materials. Here, we demonstrate a novel strategy to synthesize graphene-graphite films (GGFs) by heating butterfly wings coated with FeCl₃ in N₂, in which the full power of natural organisms is utilized. The wings work not only as an element source for GGF generation but also as a porous supporting structure for effective nitrogen doping, two-dimensional spreading, and double-face exposure of the GGFs. These GGFs exhibit a half-wave potential of 0.942 V and a H₂O₂ yield of < 0.07% for ORR electrocatalysis; these values are comparable to those for the best commercial Pt/C and all previously reported ORR catalysts in alkaline media. This two-in-one strategy is also successful with cicada and dragonfly wings, indicating that it is a universal, green, and cost-effective method for developing high-performance graphene-based materials.