Photoelectrochemical Solar Energy Conversion and Electrocatalysis Using Earth-Abundant Nanomaterials

The scale of renewable energy challenge not only calls for highly efficient technologies but also abundant, inexpensive, and robust materials. Nanomaterials can help to mitigate the poor properties of earth-abundant semiconductors and catalysts to enhance solar energy conversion. We have controlled the nanostructures and polymorphs of layered MS₂ (M = Mo, W) materials and other earth-abundant metal chalcogenides, such as metallic cobalt pyrite (CoS₂), to significantly enhance their catalytic activity in hydrogen evolution reaction (HER). We further establish ternary pyrite-type cobalt phosphosulfide (CoPS) as a high-performance earth-abundant HER catalyst that achieves geometrical catalytic current density of 10 mA/cm² at overpotentials as low as 48 mV with outstanding long-term operation stability. These earth-abundant catalysts and semiconductors have been integrated to enable efficient solar energy conversion. Integrated photocathodes of the novel earth-abundant catalysts on n⁺-p-p⁺ silicon micropyramids achieved high photocurrents up to 35 mA/cm² and onset photovoltages as high as 450 mV vs RHE, and 5-6% solar-to-hydrogen conversion efficiency.