Engineering a Co/Co2P Mott–Schottky heterostructure encased in a hollow N-doped carbon polyhedron as an advanced nanoreactor towards high-efficiency electrocatalytic oxygen evolution

Abstract

Rational exploration of earth-abundant, highly active and stable non-noble metal electrocatalysts toward the oxygen evolution reaction (OER) through the compositional manipulation and nano-architectural design is of great significance for the development of renewable energy technologies. Herein, an advanced nanoreactor composed of Co/Co₂P heterostructured nanoparticles in situ confined in N-doped carbon hollow rhombic dodecahedrons (denoted as Co/Co₂P@N-CHRDs hereafter) was elaborately designed as a high-efficiency OER electrocatalyst through a feasible self-sacrificial template method. The construction of Co/Co₂P metal/semiconductor Mott–Schottky heterojunctions could effectively trigger the spontaneous charge redistribution at the heterointerfaces, which is beneficial to enhance the charge transfer rate, tailor the adsorption behaviors of the OER intermediates, and thus ultimately improve the intrinsic activity. Moreover, the intimate coupling of Co/Co₂P heteroparticles with a porous and hollow carbon matrix with abundant open interior voids allows stabilizing the active sites, enriching the accessibility of active species, and shortening mass diffusion pathways. Benefiting from the favorable compositional and morphological merits, the elaborate Co/Co₂P@N-CHRDs exhibit distinguished OER performance in alkaline electrolytes, requiring an overpotential of 267 mV at 10 mA cm⁻² and demonstrating superb long-term durability. More impressively, a Pt/C + Co/Co₂P@N-CHRD-equipped Zn–air battery delivers a lower charge polarization curve and remarkable prolonged stability over 593 cycles as compared with the commercial Pt/C + RuO₂-based counterpart, holding promising practicability in real-life energy conversion devices. The simultaneous implementation of the Mott–Schottky effect, nano-hollowing design, and carbon hybridization may inspire the future design of affordable and practicable electrocatalysts.