N-doped CNT as electron transport promoter by bridging CoP and carbon cloth toward enhanced alkaline hydrogen evolution

Abstract

The sluggish surface reaction kinetics and slow carrier migration dynamics are the main limiting factors to implement the practical application of hydrogen evolution reaction (HER). Herein, CoP/N-CNT/CC electrocatalyst was prepared by cladding CoP nanosheets on the 3D nanostructured current collector (N-CNT/CC), which was fabricated by in-situ growing N-doped carbon nanotubes on carbon cloth (CC) substrate. The experimental results indicate that, for CoP/N-CNT/CC, CoP acts as the dominant active center to participate in HER directly, while N-CNTs are regarded as the electron transport promoter. Compared with CoP/CC that does not contain N-CNTs, CoP/N-CNT/CC possesses the lower charge-transfer resistance, revealing that N-CNT greatly accelerates electron transport, resulting in accelerating the dynamic process of carrier migration. Besides, the introduction of N-CNTs on CC can increase electrochemical active surface area and facilitate to exposure of more CoP active sites. DFT calculation demonstrates that the adsorption of H* over CoP/N-CNT/CC can be accelerated due to the weaker hydrogen adsorption energy. It proves that the HER kinetics can be accelerated when introducing the N-CNT electron transport promoter bridging CoP and CC. Therefore, CoP/N-CNT/CC electrocatalyst exhibits a η10 value of 41 mV under alkaline media, which is much better than CoP/CC (100 mV), and it shows a comparable HER activity with Pt/C at high current density.