Mott-Schottky heterojunction of Co/Co2P with built-in electric fields for bifunctional oxygen electrocatalysis and zinc-air battery

A Mott-Schottky Co/Co2P@NPCNTs nanocatalyst with a built-in electric field and enhanced mass transfer has been fabricated via a mechanochemistry-pyrolysis method for bifunctional oxygen electrocatalysis, which holds a potential to be a general approach for the fabrication of various functional nanomaterials. [Display omitted] •Mott-Schottky Co/Co2P electrocatalyst was synthesized by a mechanochemistry-pyrolysis approach.•Mott-Schottky Co/Co2P heterojunctions are encapsulated in NPCNTs to improve mass transfer.•The catalyst exhibits outstanding performance for bifunctional oxygen electrocatalysis and ZABs.•Theoretical calculation was done to elucidate the origin of the excellent property.•The built-in electric fields from Co metal to Co2P semiconductor may be the key factor. In this contribution, a high-performance bifunctional electrocatalyst composed of Co/Co2P nanoparticles encapsulated in nitrogen and phosphorus co-doped carbon nanotubes (NPCNTs) has been synthesized via a mechanochemistry-pyrolysis approach. The Schottky effect of metal-semiconductor heterojunction affords a built-in electric field at the interfaces to enhance electron transport, whereas the intertwined structure of one-dimensional (1D) NPCNTs facilitates the mass transfer of reactants and intermediates. Therefore, the as-prepared Co/Co2P@NPCNTs catalyst exhibits outstanding bifunctional ORR/OER activities, which are superior to those of commercial Pt/C and RuO2. It can also deliver a high power density and cycling life when used as the cathode for rechargeable ZABs. Theoretical calculation confirms that the spontaneous electron transport from Co to Co2P enables an up-shifted d-band center of Co/Co2P heterojunctions, which is beneficial for the intermediate adsorption in electrocatalytic process.