Lignin-Derived CoO-Ni7P3@C Heterojunction Electrocatalysts with Excellent Oxygen Evolution Reaction Properties Prepared by a Simple and Scale-Up In Situ Method

Oxygen evolution reaction (OER) is a key step that affects the efficiency of energy conversion and storage technologies such as metal-air batteries, water splitting, and fuel cells. The development of highly efficient and low-cost OER catalysts using inexpensive transition metals is critical but still challenging. In this work, lignin was phosphating modified and coordinated with metal ions to form a macromolecular framework material to obtain lignin-based CoO-Ni7P3@C heterojunction electrocatalysts as efficient OER electrocatalysts. The catalyst exhibits excellent OER activity, with a low overpotential of 180 mV and a Tafel slope of 76 mV·dec–1 at a current density of 10 mA·cm–2. In addition, CoO-Ni7P3@C exhibits satisfactory 100 h stability in alkaline electrolytes, which is attributed to excellent electron transport performance and the rich porous structure. This work reports that an OER electrocatalyst with good working stability and high activity was designed and constructed in a simple method and low cost. It has important research implications for both the high-value and efficient utilization of biomass from lignin and the controlled construction of carbon-based nonprecious metal electrocatalysts.