Electrosynthesis of CuO Nanocrystal Array as a Highly Efficient and Stable Electrocatalyst for Oxygen Evolution Reaction

Electrodeposition of active catalysts on electrodes appears as a convenient approach to prepare non-noble-metal based electrocatalysts with defined micro- and nano-structures. Herein we report a new strategy of fabricating a 3-D hierarchical CuO nanocrystal array (CuO NCA) on Cu foam through a two-step sacrifice-template method. This CuO NCA possesses high conductivity, great stability, and impressive catalytic activity for oxygen evolution reaction (OER) in alkaline electrolytes. The CuO NCA can achieve a high current density of 100 mA/cm2 at a relatively low overpotential of 400 mV for OER, which shows a better performance than other Cu-based OER catalysts and IrO2. The high activity of CuO NCA is well retained during a 10-h OER test at a high current density around 270 mA/cm2, which is about 10 times higher than the current density achieved by IrO2 (around 25 mA/cm2) with the same applied overpotential. According to our best knowledge, CuO NCA is currently the most efficient and stable Cu-based electrocatalyst for water oxidation in alkaline electrolytes.

Unraveling the role of NiSnPH@OOH/CC perovskite hydroxide for efficient electrocatalytic oxidation of methanol to formate

The sluggish kinetics of oxygen evolution reaction(OER)is the key tailback for hydrogen production from the water electrolysis.Masking OER with thermodynamically auspicious methanol oxidation reaction(MOR)can significantly boost the H_(2) and value-added products production.However,it is currently challenging to achieve a synergistic manipulation of product selectivity and performance for MOR electrocatalyst.Herein,we report NiSnPH@OOH/CC(CC=carbon cloth)perovskite hydroxide nanosphere as an efficient MOR electrocatalyst with high activity,stability,and selectivity towards methanol oxidation to formate.A surface amorphous layer of defect rich NiOOH was generated in operando by selective Sn leaching with stable perovskite hydroxide bulk structure,which mitigates the oxidative power and optimizes the local coordination environment of the active NiOOH sites.In situ Raman combined with electrochemical studies further confirm the key active species,NiOOH,generated in operando enhance the MOR and blocking the over oxidation of methanol to CO_(2).As a result,NiSnPH@OOH/CC effectively masks the OER and attains>99%selectivity with 100%Faradic efficiency for methanol-to-formate.The results of this study show the advances of NiSnPH@OOH/CC as an efficient electrocatalyst for MOR and also suggest its potential applications for various small organic molecules oxidation.

Facile sol-gel preparation of high-entropy multielemental electrocatalysts for efficient oxidation of methanol and urea

High-entropy multi-elemental(HEM)electrocatalysts present superior catalytic performance due to the efficient synergism of their components.HEM electrocatalysts are usually prepared through hydrothermal reactions or calcination,which could generate undesired heterogeneous structures that hinder the exploration of the structure–property relationship of these HEM electrocatalysts.Herein,we report a sol-gel method to synthesize homogeneous HEM electrocatalysts for electro-oxidation of methanol and urea(methanol oxidation reaction(MOR)and urea oxidation reaction(UOR)),through an acid-catalyzed gelation at room temperature.With Ni as the primary component for MOR and UOR,Co can reduce the overpotentials,while Fe can increase the catalytic activities and durability.Borate and phosphate can tune the charge distribution in active sites and speed up the reaction kinetics through fast proton transfer.Thus,the optimal Ni_(2)Fe_(0.5)Co_(0.5)-BP HEM catalyst demonstrates superior catalytic activity together with good durability and great resistance to CO poisoning.In addition,a direct methanol fuel cell with Ni_(2)Fe_(0.5)Co_(0.5)-BP electrode can not only provide power,but also produce formic acid with high yield and high Faraday efficiency.This work presents a simple strategy to prepare high-performance HEM electrocatalysts for fuel cells and production of valueadded chemicals.