Intensified Kirkendall effect assisted construction of double-shell hollow Cu-doped CoP nanoparticles anchored by carbon arrays for water splitting

Precisely engineering the architectures of nanoparticles (NPs) to optimize their physicochemical properties and thus electrocatalytic performances are challenging for scientists. Here, we report the controllable construction of solid, hollow, and double-shell hollow metal phosphide NPs anchored by carbon nanosheet arrays on carbon cloth. We demonstrate that Cu doping can intensify the nanoscale Kirkendall effect, which promotes the transformation from solid CuCo to double-shell hollow CoP NPs. Benefiting from its high dispersity, large electrochemical specific surface area, fast mass diffusion and good conductivity, the optimal double-shell hollow Cu-CoP-based electrocatalyst exhibits excellent activities for OER (η10 =176 mV) and water splitting (1.494 V @ 10 mA) in 1.0 M KOH with favorable stability. DFT calculations further confirm the optimized OH* adsorption energy of Cu-CoOOH/Cu-CoP due to Cu doping and interfacial synergy for boosting OER. This work provides new perspectives for engineering the nanoarchitecture of multilevel hollow NPs through the Kirkendall effect for electrocatalysis.