Oriented Growth of ZIF-67 to Derive 2D Porous CoPO Nanosheets for Electrochemical-/Photovoltage-Driven Overall Water Splitting

Hydrogen generation from water splitting driven by electric/solar energy is highly desirable, which requires efficient and robust bifunctional electrocatalysts for both hydrogen and oxygen evolution reactions. 2D porous hybrids with attractive chemical and structural properties are the first-class candidates for water splitting, while control over efficient and modulable synthesis remains a huge challenge. This work demonstrates a zeolitic imidazolate framework-67 (ZIF-67) nanoplate self-template approach to fabricate 2D porous oxygen-incorporated cobalt phosphide (CoPO) ultrathin nanosheets. The synthesis starts with the oriented growth of ZIF-67 nanoplates along [211] crystal plane, followed by oxidation/phosphorization processes for pore generation and O/P coincorporation in the hybrid. The resultant 2D porous CoPO nanosheets afford very small voltages of 1.52 and 1.98 V for overall water splitting at 10 and 200 mA cm(-2), respectively. This excellent bifunctionality further provides the basis for photovoltage-driven water splitting at a Faradaic efficiency of 97.6%. These findings offer a general strategy for rational design and modulation of 2D porous catalysts for various electrocatalytic and other applications.