Nanoparticle\nSuperlattices as Efficient Bifunctional\nElectrocatalysts for Water Splitting

Abstract

The\nsolar-driven water splitting process is highly attractive for\nalternative energy utilization, while developing efficient, earth-abundant,\nbifunctional catalysts for both oxygen evolution reaction and hydrogen\nevolution reaction has remained as a major challenge. Herein, we develop\nan ordered CoMnO@CN superlattice structure as an efficient bifunctional\nwater-splitting electrocatalyst, in which uniform Co–Mn oxide\n(CoMnO) nanoparticles are coated with a thin, continuous nitrogen-doped\ncarbon (CN) framework. The CoMnO nanoparticles enable optimized OER\nactivity with effective electronic structure configuration, and the\nCN framework serves as an excellent HER catalyst. Importantly, the\nordered superlattice structure is beneficial for enhanced reactive\nsites, efficient charge transfer, and structural stability. This bifunctional\nsuperlattice catalyst manifests optimized current densities and electrochemical\nstability in overall water splitting, outperforming most of the previously\nreported single- or bifunctional electrocatalysts. Combining with\na silicon photovoltaic cell, this CoMnO@CN superlattice bifunctional\ncatalyst enables unassisted solar water splitting continuously for\n∼5 days with a solar-to-hydrogen conversion efficiency of ∼8.0%.\nOur discovery suggests that these transition metal oxide-based superlattices\nmay serve as a unique structure modality for efficient bifunctional\nwater splitting electrocatalysts with scale-up potentials.