Hollow Carbon Nanopillar Arrays Encapsulated with Pd–Cu Alloy Nanoparticles for the Oxygen Evolution Reaction

Delicate design and bottom-up synthesis of hollow nanostructures for oxygen evolution electrocatalysts is a promising way to accelerate the reaction kinetics of overall water splitting. Herein, an efficient and versatile strategy for the controllable preparation of Pd–Cu alloy nanoparticles encapsulated in carbon nanopillar arrays (PD–Cu@HPCN) is developed. Core–shell structured MOF@imidazolium-based ionic polymers (ImIPs) have been prepared and adopted as a template, along with the decomposition of the inner Cu–MOFs when an anion exchange occurs between sodium tetrachloropalladate in solution and bromides in the external ImIP shell. Pd nanoparticles will be highly dispersed in the resulting Pd–Cu@HO-ImIP array, and subsequent topotactic transformation generates Pd–Cu@HNPC. No hazardous reagents or tedious steps are used to remove the inner Cu–MOF templates in contrast to the traditional top-down methods. Remarkably, the Pd–Cu@HPCN catalyst possesses outstanding oxygen evolution reaction (OER) activity, including small overpotential with 10 mA cm–2 at an overpotential of 188 mV, a large double layer capacitance (73.8 mF cm–2), and high stability (20 h). This simple, green, and efficient synthesis methodology represents a new way to design metal alloys for OER electrocatalysts or other electrocatalytic devices.