Double functionalization strategy toward Co-Fe-P hollow nanocubes for highly efficient overall water splitting with ultra-low cell voltage

Due to their inherent structural and functional defects, most bifunctional catalysts usually delivered excellent electrocatalytic activities for one half-reaction at expense of the performances for another one, thus exhibiting inconspicuous electrocatalytic abilities for overall-water-splitting. In the present work, a novel strategy of controllable assembly and synergistic catalysis based on hydrogen evolution reaction (HER) active and oxygen evolution reaction (OER) active single functional sites, was ingeniously assembled to high-performance catalysts for overall-water-splitting. Monodispersed zeolitic imidazolate framework cubes were adopted as the reaction precursors to construct bi-functional electrocatalysts through conformal Prussian blue analogue layer coating and the subsequent thermal phosphorization process. HER active Co-P and OER active Co-Fe-P hetero-components were simultaneously anchored on the shell layers of the resulted Co-Fe-P hollow nanoboxes. Benefiting from the unique structural design and functional integration, the product catalyst afforded small overpotentials of 174 and 53 mV at 10 mA/cm(2) for the OER and HER in alkaline media, respectively and a ultra-low operating cell voltage of 1.46 V for overall-water-splitting, superior to most recently reported striking bi-functional electrocatalysts. Moreover, its ultrastable catalytic activity was also impressive, delivering only negligible performance loss after a 24 h durability testing. More broadly, this combined double functionalization concept and nanoscale hollowing design is unique and advantageous, especially suitable for developing highly active and durable electrocatalysts of energy conversion reactions.

Automated summary

A novel strategy based on controllable assembly and synergistic catalysis of HER and OER active single functional sites was utilized to create high-performance catalysts for overall-water-splitting. The product catalyst exhibited superior electrocatalytic activity in alkaline media, with small overpotentials for OER and HER and ultra-low operating cell voltage for overall-water-splitting, surpassing most recently reported bifunctional electrocatalysts. This unique design is advantageous for developing highly active and durable electrocatalysts of energy conversion reactions.