Abstract
The constructure of a heterostructured interface is an effective way to design highly durable and efficient water oxidation electrocatalysts. Herein, Cu/CuCN with heterointerfaces is the first synthesized case through a simple epitaxial-like growth method, displaying superior activity and stability under pH-universal media. Associated with high electron transport and transfer of the epitaxial interfacial area, the Cu/CuCN pre-catalyst is applied to deliver the oxygen evolution reaction (OER) with lower overpotentials of 250 mV (forward scan) and 380 mV (backward scan) at 10 mA cm–2 and demonstrates better intrinsic activity (jECSA of 1.0 mA cm–2 at 420 mV) and impressive stability (136 h) in 1.0 M KOH, which exceeds most previous catalysts. Even using a nominal voltage of 1.5 V of a AA battery can drive the overall water-splitting setup. Experiments combined with theoretical simulations further uncover the existence of CuO species at the heterointerface during basic OER, which is evidence of better OER performance with abundant active sites that accelerate the conversion kinetics.
Highlights
Hydrogen (H2) due to its high energy density, renewability, and ecofriendly traits is believed to be a good choice to replace fossil fuels to address energy and environmental issues.[1,2] In general, electrochemically driven water splitting into H2 and O2 is an emerging strategy based on the occurrence of two main reactions: the hydrogen and oxygen production reaction
It is common knowledge that it is the anode oxygen evolution reaction (OER) that mainly limits the efficiency of water splitting because of its slow dynamics where water is oxidized to O2.3 At the same time, noble metal-based oxides are usually used as excellent OER
The results of SEM and powder X-ray diffraction (PXRD) from Cu(NO3)[2] as a copper source precursor indicated that almost no highly active CuCN is present in the catalyst (Figures S11−S16)
Summary
The fast OER reaction kinetics of Cu/CuCN was reflected by a lower resistance of 7.0 Ω at 1.53 V vs RHE (Figure S33), while the charge transfer resistance was 9.0 Ω for Cu NPs. Apart from the excellent OER performance, stability is an essential factor to be considered for a superior catalyst. The results of PXRD and XPS after 1000 cycles demonstrated that the formation of Cu2+1O species originated from the partial oxidation of CuCN during the OER test (Figure S36).[58,59]
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