RESUMO
The modulation of electron density is an effective option for efficient alternative electrocatalysts. Here, p-n junctions are constructed in 3D free-standing FeNi-LDH/CoP/carbon cloth (CC) electrode (LDH=layered double hydroxide). The positively charged FeNi-LDH in the space-charge region can significantly boost oxygen evolution reaction. Therefore, the j at 1.485â V (vs. RHE) of FeNi-LDH/CoP/CC achieves ca. 10-fold and ca. 100-fold increases compared to those of FeNi-LDH/CC and CoP/CC, respectively. Density functional theory calculation reveals OH- has a stronger trend to adsorb on the surface of FeNi-LDH side in the p-n junction compared to individual FeNi-LDH further verifying the synergistic effect in the p-n junction. Additionally, it represents excellent activity toward water splitting. The utilization of heterojunctions would open up an entirely new possibility to purposefully regulate the electronic structure of active sites and promote their catalytic activities.
RESUMO
Electrodeposition of abundant metals to fabricate efficient and durable electrodes indicate a viable role in advancing renewable electrochemical energy tools. Herein, we deposit Co9S8-Ag-Ni3S2@NF on nickel foam (NF) to produce Co9S8-Ag-Ni3S2@NF as a exceedingly proficient electrode for oxygen evolution reaction (OER). The electrochemical investigation verifies that the Co9S8-Ag-Ni3S2@NF electrode reveals better electrocatalytic activity to OER because of its nanoflowers' open-pore morphology, reduced overpotential (η10=125â mV), smaller charge transfer resistance, long-term stability, and a synergistic effect between various components, which allows the reactants to be more easily absorbed and subsequently converted into gaseous products during the water electrolysis route. Density functional theory (DFT) calculation as well reveals the introduction of Ag (222) surface into the Co9S8 (440)-Ni3S2 (120) structure increases the electronic density of states (DOS) per unit cell of a system and increases the electrocatalytic activity of OER by considerably lowering the energy barriers of its intermediates. This study provides the innovation of employing trimetallic nanomaterials immobilized on a conductive, continuous porous three-dimensional network formed on a nickel foam (NF) substrate as a highly proficient catalyst for OER.
RESUMO
A stable artificial solid electrolyte interphase (ASEI) containing phosphazene and perfluoroalkoxy groups was designed to protect Li anodes. The ASEI with high ionic conductivity and mechanical robustness successfully suppressed the growth of Li dendrites, significantly enhancing the electrochemical performance of the Li-O2 batteries.
RESUMO
Aqueous polysulfide/iodide redox flow batteries are attractive for scalable energy storage due to their high energy density and low cost. However, their energy efficiency and power density are usually limited by poor electrochemical kinetics of the redox reactions of polysulfide/iodide ions on graphite electrodes, which has become the main obstacle for their practical applications. Here, CoS2/CoS heterojunction nanoparticles with uneven charge distribution, which are synthesized in situ on graphite felt by a one-step solvothermal process, can significantly boost electrocatalytic activities of I-/I3- and S2-/Sx2- redox reactions by improving absorptivity of charged ions and promoting charge transfer. The polysulfide/iodide flow battery with the graphene felt-CoS2/CoS heterojunction can deliver a high energy efficiency of 84.5% at a current density of 10 mA cm-2, a power density of 86.2 mW cm-2 and a stable energy efficiency retention of 96% after approximately 1000 h of continuous operation.