Interface engineering of mesoporous triphasic cobalt-copper phosphides as active electrocatalysts for overall water splitting

Efficient electrocatalysts for water splitting are essential for viable generation of highly purified hydrogen. Hence there is a need to develop robust catalysts to eliminate barriers associated with sluggish kinetics associated with both anodic oxygen and cathodic hydrogen evolution reactions. Herein, we report a two-step nanocasting-solid phase phosphorization approach to generate ordered mesoporous triphasic phosphides CoP@Cu2P-Cu3P. We show that it is a highly efficient bifunctional electrocatalyst useful for overall water splitting. The mesoporous triphasic CoP@Cu2P-Cu3P only requires a low overpotential of 255 mV and 188 mV to achieve 10 mA cm(-2) for oxygen and hydrogen evolution reactions, respectively. The combination of mesoporous pores (similar to 5.6 nm) with very thin walls (similar to 3.7 nm) and conductive networks in triphasic CoP@Cu2P-Cu3P enable rapid rate of electron transfer and mass transfer. In addition, when CoP@Cu2P-Cu3P is used to fabricate symmetric electrodes, the high surface area mesoporous structure and synergetic effects between phases together contribute to a low cell voltage of 1.54 V to drive a current density 10 mA cm(-2). This performance is superior to noble-metal-based Pt/C-IrO2/C. This work provides a new approach for the facile design and application of multiphase phosphides as highly active bifunctional and stable electrocatalysts for water-alkali electrolyzers.

Automated summary

The study introduces a new approach for designing efficient electrocatalysts for overall water splitting. A two-step nanocasting-solid phase phosphorization method was used to create highly efficient triphasic phosphide catalysts with excellent electron transfer and mass transfer properties, enabling low-voltage operation at high current densities.