N-doped TiO nanotube arrays with uniformly embedded Co P nanoparticles for high-efficiency hydrogen evolution reaction.

Efficient and stable non-precious metal based electrocatalysts are crucial to the hydrogen evolution reaction (HER) in renewable energy conversion. Herein, Co P nanoparticles (NPs) are uniformly embedded in N-doped TiO nanotube arrays (Co P/N-TiO NTAs) by low-temperature phosphorization of the precursor of metallic cobalt NPs embedded in N-doped TiO NTAs (Co/N-TiO NTAs) which were fabricated by phase separation of CoTiO NTAs in ammonia. Owing to the abundant exposed surface active sites of Co P NPs, tight contact between the Co P NPs and TiO NTAs, fast electron transfer in N-doped TiO, and channels for effective diffusion of ions and H bubbles in the tubular structure, the Co P/N-TiO NTAs have excellent electrocatalytic activity in HER exemplified by a low overpotential of 180 mV at 10 mA cm and small Tafel slope of 51 mV dec in 0.5 M HSO. The catalyst also shows long-term cycling stability and is a promising non-precious metal catalyst for HER.