Phase control and stabilization of 1T-MoS2 via black TiO2-x nanotube arrays supporting for electrocatalytic hydrogen evolution

1T phase MoS2 (1T-MoS2) is a promising substitute of platinum electrocatalyst for hydrogen evolution reaction (HER) due to its high intrinsic activity but suffering from thermodynamical instability. Although great efforts have been made to synthesize 1T-MoS2 and enhance its stability, it remains a big challenge to realize the phase control and stabilization of 1T-MoS2. Herein, based on crystal field theory analysis, we propose a new solution by designing an electrocatalyst of 1T-MoS2 nanosheets anchoring on black TiO2-x nanotube arrays in-situ grown on Ti plate (1T-MoS2/TiO2-x@Ti). The black TiO2-x substrate is expected to play as electron donors to increase the charge in Mo 4d orbits of 1T-MoS2 and thus weaken the asymmetric occupation of electrons in the Mo 4d orbits. Experimental results demonstrate that black TiO2-x nanotubes shift electrons to MoS2 and induce MoS2 to generate more 1T phase due to stabilizing the 1T-MoS2 nanosheets compared with a Ti substrate. Thus 1T-MoS2/TiO2-x@Ti shows much improved HER performance with a small Tafel slope of 42 mV dec(-1) and excellent catalytic stability with negligible degradation for 24 h. Theoretical calculations confirm that the black TiO2-x substrate can effectively stabilize metastable 1T-MoS2 due to electrons transferring from black TiO2-x to Mo 4d orbits. This work sheds light on the instability of 1T-MoS2 and provides an essential method to stabilize and efficiently utilize 1T-MoS2 for HER. (c) 2021 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

This study proposes a new solution for the thermodynamic instability of 1T-MoS2 by designing an electrocatalyst of 1T-MoS2 nanosheets anchored on black TiO2-x nanotube arrays grown in-situ on a Ti plate. Experimental and theoretical results demonstrate that the black TiO2-x substrate effectively stabilizes the metastable 1T-MoS2 and improves the hydrogen evolution reaction performance.