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It is highly attractive to develop efficient water electrolysis route to implement hydrogen generation in a low‐cost way, which while requires excess energy to surmount the activation barriers majorly limited by oxygen evolution reaction at anode side. Herein, we report an acid‐alkali asymmetric‐electrolyte electrolyzer (AAAE) that can achieve substantial energy saving for electrolysis hydrogen generation, thanks to the assistance of electrochemical neutralization energy (ENE) and urea oxidation reaction (UOR). To this end, free‐standing Ni(OH)2 nanosheets on carbon cloth (Ni(OH)2−NSs/CC) is fabricated as catalytic anode for alkaline UOR, which manifests impressively high catalytic activity with delivering 10 mA cm−2 at 1.32 V and long‐term durability. The as‐developed AAAE only requires an applied voltage of 0.66 V to release the electrolysis current of 10 mA cm−2, yielding the H2 Faraday efficiency close to 100 % along with H2 production rate of 183.8 μmol h−1. [ABSTRACT FROM AUTHOR]

Developing efficient and low‐cost catalysts with excellent catalytic activities for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of significance for large‐scale commercial applications in rechargeable Zn−air batteries and fuel cells. Herein, we develop a simple, mild and efficient method to synthesize a hybrid of N‐doped carbon nanosheets encapsulating cobalt nanoparticles (Co@NCNSs), which shows favorable catalytic properties toward both ORR and OER with high activity and good stability. The optimized hybrids (Co@NCNSs‐900) exhibit an onset potential of 0.95 V vs. reversible hydrogen electrode (RHE) and a half‐wave potential of 0.85 V vs. RHE for the ORR, and an onset potential of 1.51 V vs. RHE, a potential of 1.59 V vs. RHE at 10 mA cm−2 for the OER, as well as an oxygen electrode activity parameter (ΔE) of 0.802 V in alkaline electrolyte. Moreover, the Zn−air battery with the Co@NCNSs‐900 as the cathode catalyst outperforms that with the commercial Pt/C as cathode catalyst in terms of the maximum power density and stability, showing great prospects in renewable energy applications. [ABSTRACT FROM AUTHOR]

Hydrogen, as the one of clean energy source, has the advantages of high energy density and carbon-free emission. Water electrolysis is one of the most promising ways to generate hydrogen, but the rather high energy required seriously hinders its widespread applications yet. In this study, we report an alkaline electrolyzer to implement energy-saving H 2 generation by coupling cathodic hydrogen evolution reaction (HER) with anodic glucose oxidation reaction (GOR) other than oxygen evolution reaction, in which nickel-doped MoS 2 nanoparticles (Ni–MoS 2 NPs) has been developed as bifunctional electrocatalyst for HER and GOR. The electrolyzer only requires a cell voltage of 1.67 V to reach an electrolysis current density of 10 mA cm−2, about 270 mV lower than the corresponding value in the traditional electrolyzer. Electrolytic H 2 generation with the assistance of biomass derived materials may open a new way for the future sustainable development. • Ni-doped MoS 2 was fabricated as bifunctional electrocatalyst. • Biomass derived glucose as the electron donor to replace water. • Glucose assisted electrolytic H 2 generation can reduce energy consumption. [ABSTRACT FROM AUTHOR]

Transforming carbon dioxide (CO 2) into valuable fuels or chemicals through electrolysis represents a promising approach to reduce the carbon footprint. Conventional CO 2 electrolysis yet faces a challenge in low energy efficiency due to the energy-intensive oxygen evolution reaction (OER) occurring at the anode. In this study, we present an advanced CO 2 electrolysis system that pairs cathodic CO 2 reduction with anodic degradation of hydrazine oxidation reaction (HzOR), enabling efficient CO 2 electrolysis at an ultra-low voltage. To achieve this objective, two precious-metal-free electrocatalysts have been designed and fabricated. Specifically, a nickel single-atom catalyst anchored on porous carbon nanofibers has been developed for cathodic CO 2 -to-CO conversion, while a flower-like Ni 2 Fe 2 N catalyst grown in-situ on nickel foam has been developed for anodic HzOR. We demonstrate high efficiency of CO production (FE CO > 80%) at 100 mA cm−2 with an applied voltage of only 0.45 V by simultaneously degrading hydrazine in a flow cell. [Display omitted] • A promising green electrolyzer coupling CO 2 reduction reaction with hydrazine oxidation reaction (HzOR) was proposed. • The single atomic nickel anchored on porous carbon nanofiber (NiSACs-PCNF) was developed as highly active CO 2 RR catalyst. • The flower-like Ni 2 Fe 2 N in-situ grown on nickel foam (Ni 2 Fe 2 N/NF) was prepared as the effective HzOR catalyst. • The assembled electrolyzer achieved efficient CO production and hydrazine degradation at an ultralow voltage of 0.45 V. • The designed electrolyzer provided a new route for coupling energy-efficient CO 2 upgradation with waste degradation. [ABSTRACT FROM AUTHOR]

Optimized electrocatalyst that hybrids with carbon coating FeCoP x nanoparticles possesses catalytic activity toward ORR, OER and HER. Furthermore, through the design of alkali-acid electrolyzer and device integration, for the very first time, a single Zinc-air battery enable to drive an alkali-acid electrolyzer for producing hydrogen and oxygen. [Display omitted] • A one-pot scalable pyrolysis strategy to fabricate a tri-functional electrocatalyst. • High catalytic activity toward ORR&OER in alkaline and HER in acidic media. • The Zn-air battery can run stably for 1500 cycles. • An alkali-acid electrolyzer only requires 0.99 V to release an electrolysis current density of 10 mA cm−2. • A single self-made Zinc-air battery can drive an alkali-acid electrolyzer to produce hydrogen. Developing handy synthesis routes to fabricate low-cost, high-activity, and multifunctional electrocatalysts for a variety of electrochemical reactions is highly desirable so as to achieve the goal that one catalyst can be used for integrated electrolysis devices, thus greatly simplifying the electrocatalyst system processing. Here, we report a one-pot scalable pyrolysis strategy to fabricate a tri-functional electrocatalyst, i.e. , hybrids with carbon coating FeCoP x nanoparticles, which shows favorable electrocatalytic properties toward oxygen reduction reaction, oxygen evolution reaction in alkaline solution, and hydrogen evolution reaction in acidic condition. The new synthesis routes enable us to readily develop an integrated device with a Zn-air battery driving an alkali-acid electrolyzer by just using one catalyst. The present work may shed light on the practical viability of the development of multifunctional electrocatalysts for integrated devices applications. [ABSTRACT FROM AUTHOR]