In Situ Replacement Synthesis of Co@NCNT Encapsulated CoPt3@Co2P Heterojunction Boosting Methanol Oxidation and Hydrogen Evolution

Simultaneous boosting electrochemical methanol oxidation reaction (MOR) for direct methanol fuel cells and production of hydrogen is meaningful but challenging. Herein, a sea urchin-shaped cobalt-embedded N-doped carbon nanotubes (Co@NCNT) encapsulated CoPt3 @Co2 P heterojunction (CoPt3 @Co2 P/Co@NCNT) is fabricated. Theoretical calculations confirm that electrons at the interfaces transfer from CoPt3 to Co2 P, where electron hole region on CoPt3 is beneficial to improving the MOR activity, whereas accumulation region on Co2 P favors to the optimization of H2 O and H* absorption energies for hydrogen evolution reaction (HER). Benefitting from its interfacial electronic reconfiguration, the CoPt3 @Co2 P/Co@NCNT heterojunction exhibits excellent electrocatalytic performances for MOR and HER, in which the mass activity (2981 mA mgPt-1 ) for MOR is 14.2 times than that of Pt/C (20%), and the smallest overpotentials only requires 19 mV to deliver a current density of 10 mA cm-2 for HER. Moreover, the electrolyzer employing CoPt3 @Co2 P/Co@NCNT for anodic MOR and cathodic H2 production only requires a low voltage of 1.43 V at 10 mA cm-2 with impressive long-life cycling stability, which is obviously better than that of commercial Pt/C//RuO2 . This study offers a novel strategy for other organics oxidation reaction coupled with HER catalyzed production of hydrogen.