Interfacial Engineering of W2N/WC Heterostructures Derived from Solid‐State Synthesis: A Highly Efficient Trifunctional Electrocatalyst for ORR, OER, and HER

To meet the practical demand of overall water splitting and regenerative metal–air batteries, highly efficient, low‐cost, and durable electrocatalysts for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) are required to displace noble metal catalysts. In this work, a facile solid‐state synthesis strategy is developed to construct the interfacial engineering of W2N/WC heterostructures, in which abundant interfaces are formed. Under high temperature (800 °C), volatile CNx species from dicyanodiamide are trapped by WO3 nanorods, followed by simultaneous nitridation and carbonization, to form W2N/WC heterostructure catalysts. The resultant W2N/WC heterostructure catalysts exhibit an efficient and stable electrocatalytic performance toward the ORR, OER, and HER, including a half‐wave potential of 0.81 V (ORR) and a low overpotential at 10 mA cm−2 for the OER (320 mV) and HER (148.5 mV). Furthermore, a W2N/WC‐based Zn–air battery shows outstanding high power density (172 mW cm−2). Density functional theory and X‐ray absorption fine structure analysis computations reveal that W2N/WC interfaces synergistically facilitate transport and separation of charge, thus accelerating the electrochemical ORR, OER, and HER. This work paves a novel avenue for constructing efficient and low‐cost electrocatalysts for electrochemical energy devices. Interfacial engineering of W2N/WC heterostructures for ORR, OER, and HER via a facile and practical solid‐state synthesis strategy is investigated. W2N/WC heterostructures exhibit superior electrochemical activity and stability. Such W2N/WC heterostructures catalysts also exhibit remarkable performance for Zn–air batteries and overall water splitting. This work paves a new way for constructing the electrocatalyst in electrochemical energy devices.