Interface engineering of Co nanoparticles decorated by Ir confined in N-doped carbon nanotubes for flexible Zn–air batteries and pH-universal overall water splitting

To alleviate the crisis of energy shortages, the scalable fabrication of highly efficient electrocatalysts is highly sought after for metal–air batteries and pH-universal overall water splitting. Hereby, an in situ construction to achieve Co@Ir nanoparticles in N-doped carbon nanotubes has been explored, which were directly fabricated by the pyrolysis and galvanic replacement. The interface engineering of Co@Ir core–shell structures could enhance interfacial and synergistic effects, achieving the tailorable electrocatalytic activities for oxygen reduction reaction, oxygen evolution reaction and hydrogen evolution reaction. Co@Ir-NT demonstrates the outstanding stability for overall water splitting under pH-universal conditions. Co@Ir-NT-based r-ZABs display a high power density of 295.1 mW·cm⁻² and a ultralong cycle stability over 2000 continuous charge–discharge cycles, and Co@Ir-NT-based F-ZABs maintain the similar performance at different bending angles, suggesting its promising potential in the application of wearable electronics. The corresponding theoretical calculations also indicate that Co@Ir core–shell structure could improve the adsorption capacity and facilitate the breakage of O–O band. Hence, this work might be helpful for developing multifunctional catalysts for metal–air batteries and water splitting under pH-universal conditions.