Co Nanoparticles@N-doped carbon coated on carbon Nanotube@Defective silica as non-noble photocathode for efficient photoelectrochemical hydrogen generation

The development of photoelectrodes capable of light-driven hydrogen evolution from water with non-noble metals is an important approach for the storage of solar energy in the form of a chemical energy carrier. In this study, we report Co nanoparticles@N-doped carbon coated on carbon nanotube@defective-silica (CNTs@Co@NC/D-SiO2), which are composed of Co nanoparticles@N-doped carbon as electrocatalyst, defective-silica as photocatalyst and carbon nanotube as conductive substrates. The obtained non-noble photocathode possesses the high performance for efficient photoelectrochemical hydrogen evolution reaction. When evaluated for hydrogen evolution reaction electrocatalysis, CNTs@Co@NC/D-SiO2 exhibits a small onset overpotential of 104 mV (J = 1 mA cm−2), a Tafel slope of 69.1 mV dec−1 and outstanding long-term cycling stability. The P type semiconductor characteristics of CNTs@Co@NC/D-SiO2 due to defective-silica with carrier concentration of 3.53 × 1019 cm−3 is measured, which produces a significant positive shift of overpotential of 40 mV (J = 10 mA cm−2) under 100 mW cm−2 simulated sunlight irradiation. These findings provide a straightforward and effective route to produce cheap and efficient photo-electro-catalyst for water splitting.