Efficient Self-Powered Overall Water Splitting by Ni4 Mo/MoO2 Heterogeneous Nanorods Trifunctional Electrocatalysts

Fe nanoparticles confined by multiple-heteroatom-doped carbon frameworks for aqueous Zn-air battery driving CO2 electrolysis

Metal-organic frameworks (MOF) derived carbon materials are considered to be excellent conductive mass transfer substrates, and the large specific surface area provides a favorable platform for loading metal nanoparticles. Tuning the coordination of metals through polyacid doping to change the MOF structure and specific surface area is an advanced strategy for designing catalysts. Modification of Fe-doped ZIF-8 pre-curing by pyrolysis of phosphomolybdic acid hydrate (PMo), Fe nanoparticles confined by Mo and N co-doped carbon frameworks (Fe-NP/MNCF) were fabricated, and the impact of PMo doping on the shape and functionality of the catalysts was investigated. The Zn-air battery (ZAB) driven CO2 electrolysis was realized by using Fe-NP/MNCF, which was used as bifunctional oxygen reduction reaction (ORR) and carbon dioxide reduction reaction (CO2RR) catalysts. The results show that the half-wave potential (E1/2) of Fe-NP/MNCF is 0.89 V, and the limiting diffused current density (jL) is 6.4 mA cm-2. The ZAB constructed by Fe-NP/MNCF shows a high specific capacity of 794.8 mAh gZn-1, a high open-circuit voltage (OCV) of 1.475 V, and a high power density of 111.6 mW cm-2. Fe-NP/MNCF exhibited efficient CO2RR performance with high CO Faraday efficiency (FECO) of 87.5 % and current density for the generation of carbon dioxide (jCO) of 10 mA cm-2 at -0.9 V vs RHE. ZAB-driven CO2RR had strong catalytic stability. These findings provide new methods and techniques for the preparation of advanced carbon-based catalysts from MOFs.

Efficient Hydrogen Evolution on Antiperovskite CuNCo3 Nanowires by Mo Incorporation and its Trifunctionality for Zn Air Batteries and Overall Water Splitting

The current development of single electrocatalyst with multifunctional applications in overall water splitting (OWS) and zinc-air batteries (ZABs) is crucial for sustainable energy conversion and storage systems. However, exploring new and efficient low-cost trifunctional electrocatalysts is still a significant challenge. Herein, the antiperovskite CuNCo3 prototype, that is proved to be highly efficient in oxygen evolution reaction but severe hydrogen evolution reaction (HER) performance, is endowed with optimum HER catalytic properties by in situ-derived interfacial engineering via incorporation of molybdenum (Mo). The as-prepared Mo-CuNCo3 @CoN nanowires achieve a low HER overpotential of 58 mV@10 mA cm-2 , which is significantly higher than the pristine CuNCo3 . The assembled CuNCo3 -antiperovskite-based OWS not only entails a low overall voltage of 1.56 V@10 mA cm-2 , comparable to most recently reported metal-nitride-based OWS, but also exhibits excellent ZAB cyclic stability up to 310 h, specific capacity of 819.2 mAh g-1 , and maximum power density of 102 mW cm-2 . The as-designed antiperovskite-based ZAB could self-power the OWS system generating a high hydrogen rate, and creating opportunity for developing integrated portable multifunctional energy devices.

Self-Powered Hydrogen Production with Improved Energy Efficiency via Polysulfides Redox

In the pursuit of efficient solar-driven electrocatalytic water splitting for hydrogen production, the intrinsic challenges posed by the sluggish kinetics of anodic oxygen evolution and intermittent sunlight have prompted the need for innovative energy systems. Here, we introduce an approach by coupling the polysulfides oxidation reaction with the hydrogen evolution reaction for energy-saving H2 production, which could be powered by an aqueous zinc-polysulfides battery to construct a self-powered energy system. This unusual hybrid water electrolyzer achieves 300 mA cm-2 at a low cell voltage of 1.14 V, saving electricity consumption by 100.4% from 5.47 to 2.73 kWh per m3 H2 compared to traditional overall water splitting. Benefiting from the favorable reaction kinetics of polysulfides oxidation/reduction, the aqueous zinc-polysulfides battery exhibits an energy efficiency of approximately 89% at 1.0 mA cm-2. Specially, the zinc-polysulfide battery effectively stores intermittent solar energy as chemical energy during light reaction by solar cells. Under an unassisted light reaction, the batteries could release energy to drive H2 production through a hybrid water electrolyzer for uninterrupted hydrogen production. Therefore, the aim of simultaneously generating H2 and eliminating the restrictions of intermittent sunlight is realized by combining the merits of polysulfides redox, an aqueous metal-polysulfide battery, and solar cells. We believe that this concept and utilization of polysulfides redox will inspire further fascinating attempts for the development of sustainable energy via electrocatalytic reactions.

Modulating adsorption energy on nickel nitride-supported ruthenium nanoparticles through in-situ electrochemical activation for urea-assisted alkaline hydrogen production

The rational design of electrocatalysts with exceptional performance and durability for hydrogen production in alkaline medium is a formidable challenge. In this study, we have developed in-situ activated ruthenium nanoparticles dispersed on Ni3N nanosheets, forming a bifunctional electrocatalyst for hydrogen evolution and urea oxidation. The results of experimental analysis and theoretical calculations reveal that the enhanced hydrogen evolution reaction (HER) performance of O-Ru-Ni3N stems primarily from the optimized hydrogen adsorption and hydroxyl adsorption on Ru sites. The O-Ru-Ni3N on nickel foam (NF) electrode exhibits excellent HER performance, requiring only 29 mV to reach 10 mA cm-2 in an alkaline medium. Notably, when this O-Ru-Ni3N/NF catalyst is employed for both HER and urea oxidation reaction (UOR) to create an integrated H2 production system, a current density of 50 mA cm-2 can be generated at the cell voltage of 1.41 V. This report introduces an energy-efficient catalyst for hydrogen production and proposes a viable strategy for anodic activation in energy chemistry.