Phosphotungstic acid-assisted construction of hollow CoWO4/CoP heterostructures for efficient and durable overall water splitting

PTA-assisted precursor co-evolution couples hollowing with W incorporation. • Hollow CoWO 4 /CoP integrates porosity with strongly coupled heterointerfaces. • CoWO 4 /CoP enables efficient and durable alkaline overall water splitting. Integrating hollow-structure engineering with multicomponent regulation remains challenging for metal–organic framework-derived bifunctional electrocatalysts. Herein, a phosphotungstic acid (PTA)-assisted precursor coevolution strategy is developed to construct hollow CoWO 4 /CoP heterostructures for alkaline overall water splitting. Serving as both an acidic etchant and a W source, PTA couples framework etching and reconstruction with W incorporation into the ZIF-67-derived precursor, thereby coordinating the structural and compositional evolution of the precursor. Subsequent calcination and phosphidation transform the precursor into a porous hollow framework composed of closely integrated CoWO 4 and CoP domains. The hollow architecture increases the accessible electrode–electrolyte interface and facilitates mass transport, while electronic interactions between the oxide and phosphide components promote interfacial charge transfer. Consequently, CoWO 4 /CoP requires overpotentials of only 73 and 218 mV to deliver 10 mA cm −2 for HER and OER, respectively, and sustains OER operation at 1 A cm −2 for 500 h. When CoWO 4 /CoP is employed as both the anode and cathode, the resulting electrolyzer reaches 10 mA cm⁻² at a cell voltage of 1.52 V and operates continuously for 200 h. This work demonstrates an effective route for coordinating hollow-structure formation and composition regulation in MOF-derived multicomponent electrocatalysts.