Cation-doped sea-urchin-like MnO₂ for electrocatalytic overall water splitting

It is necessary to take full account of the activity, selectivity, dynamic performance, economic benefits, and environmental impact of the catalysts in the overall water splitting of electrocatalysis for the reasonable design of electrocatalysts. Designing nanostructures of catalysts and optimizing defect engineering are considered environmentally friendly and cost-effective electrocatalyst synthesis strategies. Herein, we report that metal cations regulate the microstructure of sea-urchin-like MnO₂ and act as dopants to cause the lattice expansion of MnO₂, resulting in crystal surface defects. The valence unsaturated Mn⁴⁺/Mn³⁺ greatly promotes the electrocatalytic oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The optimal Al-MnO₂ showed that the overpotential is 390 and 170 mV in the process of catalyzing OER and HER, respectively, at a current density of 10 mA cm^-2. It is exciting to note that after 5000 cycles of Al-MnO₂ within the kinetic potential range of OER and HER, its performance remained almost unchanged. This work provides a simple, efficient, and environmentally friendly route for the design of efficient integrated water-splitting electrocatalysts.