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Electroreduction of nitrate (NO 3 RR) to ammonia in membraneless electrolyzers is of great significance for reducing the cost and saving energy consumption. However, severe chemical crossover with side reactions makes it challenging to achieve ideal electrolysis. Herein, we propose a general strategy for efficient membraneless ammonia synthesis by screening NO 3 RR catalysts with inferior oxygen reduction activity and matching the counter electrode (CE) with good oxygen evolution activity while blocking anodic ammonia oxidation. Consequently, screening the available Co-Co system, the membraneless NO 3 - -to-NH 3 conversion performance was significantly higher than H-type cells using costly proton-exchange membranes. At 200 mA cm -2 , the full-cell voltage of the membraneless system (∼2.5 V) is 4 V lower than that of the membrane system (∼6.5 V), and the savings are 61.4 kW h (or 56.9%) per 1 kg NH 3 produced. A well-designed pulse process, inducing reversible surface reconstruction that in situ generates and restores the active Co(III) species at the working electrode and forms favorable Co 3 O 4 /CoOOH at the CE, further significantly improves NO 3 - -to-NH 3 conversion and blocks side reactions. A maximum NH 3 yield rate of 1500.9 μmol cm -2 h -1 was achieved at -0.9 V (Faraday efficiency 92.6%). This pulse-coupled membraneless strategy provides new insights into design complex electrochemical synthesis.

Electroreduction of waste nitrate to valuable ammonia offers a green solution for environmental restoration and energy storage. However, the electrochemical self-reconstruction of catalysts remains a huge challenge in terms of maintaining their stability, achieving the desired active sites, and managing metal leaching. Herein, we present an electrical pulse-driven Co surface reconstruction-coupled Co δ+ shuttle strategy for the precise in situ regulation of the Co(II)/Co(III) redox cycle on the Co-based working electrode and guiding the dissolution and redeposition of Co-based particles on the counter electrode. As result, the ammonia synthesis performance and stability are significantly promoted while cathodic hydrogen evolution and anodic ammonia oxidation in a membrane-free configuration are effectively blocked. A high rate of ammonia production of 1.4 ± 0.03 mmol cm -2 h -1 is achieved at -0.8 V in a pulsed system, and the corresponding nitrate-to-ammonia Faraday efficiency is 91.7 ± 1.0%. This work holds promise for the regulation of catalyst reactivity and selectivity by engineering in situ controllable structural and chemical transformations.

Hydrogen peroxide (H 2 O 2 ), as a critical green chemical, has received immense attention in energy and environmental fields. The ability to produce H 2 O 2 in earth-abundant water without relying on low solubility oxygen would be a sustainable and potentially economic process, applicable even to anaerobic microenvironments, such as groundwater treatment. However, the direct water to H 2 O 2 process is currently hindered by low selectivity and low production rates. Herein, we report that poly(tetrafluoroethylene) (PTFE), a commonly used inert polymer, can act as an efficient triboelectric catalyst for H 2 O 2 generation. For example, a high H 2 O 2 production rate of 24.8 mmol g cat -1 h -1 at a dosage of 0.01 g/L PTFE was achieved under the condition of pure water, ambient atmosphere, and no sacrificial agents, which exceeds the performance of state-of-the-art aqueous H 2 O 2 powder catalysts. Electron spin resonance and isotope experiments provide strong evidence that water-PTFE tribocatalysis can directly oxidize water to produce H 2 O 2 under both anaerobic and aerobic conditions, albeit with different synthetic pathways. This study demonstrates a potential strategy for green and effective tribocatalytic H 2 O 2 production that may be particularly useful toward environmental applications.

Ultrasound (US)-activated nanoagents capable of producing cytotoxic species have been promising for the treatment of deep-seated tumors; however, poor tumor uptake and insufficient generation of cytotoxic agents have largely limited their therapeutic efficacy in vivo . Herein, we report a hybrid FeCuS-lipid nanoparticle (AIBA@FeCuS-FeCO) by amphiphilic lipids-assisted emulsion of a free radical initiator (AIBA), a radical-sensitive CO donor (Fe 3 (CO) 12 ), and radical-degradable FeCuS nanodisks for US-activated synergistic therapy of deep-located orthotopic gastric tumors in living mice. Upon US irradiation, AIBA@FeCuS-FeCO could be degraded and release cytotoxic AIBA radicals, CO, Fe 2+ , and Cu 2+ , allowing us to (1) enhance tumor uptake of AIBA@FeCuS-FeCO through CO-mediated vasodilation, (2) promote hydroxyl radical production and induce tumor ferroptosis via intracellular accumulation of Fe 2+ /Cu 2+ , and (3) kill tumor cells. Moreover, the subsequent administration of disulfiram (DSF) could further chelate with the liberated Cu 2+ , yielding toxic bis( N , N -diethyl dithiocarbamato)copper(II) chelates to synergize the therapeutic effect to ablate deep-seated orthotopic gastric tumors.