A Dendritic Nanostructured Copper Oxide Electrocatalyst for the Oxygen Evolution Reaction

Abstract

International audienceTo use water as the source of electrons for proton or CO2 reduction within electrocatalytic devices, catalysts are required for facilitating the proton-coupled multi-electron oxygen evolution reaction (OER, 2 H2O→O2+4 H++4 e−). These catalysts, ideally based on cheap and earth abundant metals, have to display high activity at low overpotential and good stability and selectivity. While numerous examples of Co, Mn, and Ni catalysts were recently reported for water oxidation, only few examples were reported using copper, despite promising efficiencies. A rationally designed nanostructured copper/copper oxide electrocatalyst for OER is presented. This material derives from conductive copper foam passivated by a copper oxide layer and further nanostructured by electrodeposition of CuO nanoparticles. The generated electrodes are highly efficient for catalyzing selective water oxidation to dioxygen with an overpotential of 290 mV at 10 mA cm−2 in 1 m NaOH solution

Cu3P/CuO Core‐Shell Nanorod Arrays as High‐Performance Electrocatalysts for Water Oxidation

“…However, the intensities of the Cu 2p peaks arising from Cu 3 P were significantly decreased after electrochemical oxidation, along with the appearance of two new peaks for Cu 2p at 933.8 (2p 3/2 ) and 953.8 eV (2p 1/2 ) and the disappearance of the oxidized Cu−P signals at 934.5 (Cu 2p 3/2 ) and 954.7 eV (Cu 2p 1/2 ). These observations in combination with the appearance of O1s signal (Figure c) at 529.4 eV suggest the presence of CuO as the dominant surface species ,,. The Cu−O vibration bands at 298, 346 and 631 cm −1 in Raman spectrum in Figure d also verify the formation of CuO layer .…”

“…In contrast, much higher overpotentials were required by Cu−CuO ( η 10 =360 mV) and bare CF ( η 10 =400 mV) to reach the same current density. As listed in Table S1, the performance of Cu−Cu 3 P/CuO outperforms those of FTO‐CuO ( η 10 =475 mV), stainless steel‐2D CuO NS ( η 10 =350 mV) and Cu−Cu 2 O ( η 10 =350 mV) under the same alkaline conditions, and compares favorably to that of the best performed Cu‐based electrocatalyst Cu−Cu 2 O/CuO ( η 10 =290 mV, without iR‐compensation) . The advantage of Cu−Cu 3 P/CuO becomes more noticeable at higher current densities.…”

“…In principle, the poor conductivity of metal oxide can be alleviated by integration with highly conductive substrate. Recently, Mougel and Li have separately developed the three‐dimensional copper foams (CFs) composed of Cu−Cu 2 O core‐shell dendrites. In these studies, the conductive copper foams were fabricated by hydrogen‐evolution‐assisted electrodeposition, which combines the copper dendritic growth and the concomitant generation of foam with hydrogen bubbles as soft templates.…”

“…The porous core‐shell nanostructures possess high specific surface area and accelerate the mass transfer of electrolyte, greatly boosting the OER kinetics of copper oxide. In Mougel's work, a layer of CuO nanoparticles was further deposited on the surface of Cu−Cu 2 O to benefit the OER performance . However, the resulting electrode suffered from low stability in highly basic media such as 1.0 M NaOH solution.…”

“…The advantage of Cu−Cu 3 P/CuO becomes more noticeable at higher current densities. For example, it needs an overpotential of 390 mV (490 mV without iR‐compensation) to deliver a current density of 100 mA cm −2 , lower than those for Cu−Cu 2 O ( η 100 =470 mV, with iR‐compensation) and Cu−Cu 2 O/CuO ( η 100 =510 mV, without iR‐compensation) electrodes. In addition, the Cu−Cu 3 P/CuO electrode exhibited a Tafel slope of 74.8 mV dec −1 (Figure b) based on the steady currents between 1.55 to 1.65 V. This value is much smaller than that of Cu−CuO (119.2 mV dec −1 ), demonstrating the crucial role of incorporation of Cu 3 P in improving OER kinetics.…”