N-doped TiO2 nanotube arrays with uniformly embedded CoxP 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, CoxP nanoparticles (NPs) are uniformly embedded in N-doped TiO2 nanotube arrays (CoxP/N-TiO2 NTAs) by low-temperature phosphorization of the precursor of metallic cobalt NPs embedded in N-doped TiO2 NTAs (Co/N-TiO2 NTAs) which were fabricated by phase separation of CoTiO3 NTAs in ammonia. Owing to the abundant exposed surface active sites of CoxP NPs, tight contact between the CoxP NPs and TiO2 NTAs, fast electron transfer in N-doped TiO2, and channels for effective diffusion of ions and H2 bubbles in the tubular structure, the CoxP/N-TiO2 NTAs have excellent electrocatalytic activity in HER exemplified by a low overpotential of 180 mV at 10 mA cm−2 and small Tafel slope of 51 mV dec−1 in 0.5 M H2SO4. The catalyst also shows long-term cycling stability and is a promising non-precious metal catalyst for HER.