Targeted bottom-up synthesis of 1T-phase MoS2 arrays with high electrocatalytic hydrogen evolution activity by simultaneous structure and morphology engineering

摘要

The incorporation of small guest molecules or ions by bottom-up hydrothermal synthesis has recently emerged as a promising new way to engineer 1T-phase MoS2 with high hydrogen evolution reaction (HER) activity.However,the mechanism of the associated structural evolution remains elusive and controversial,leading to a lack of effective routes to prepare 1T-phase MoS2 with controlled structure and morphology,along with high purity and stability.Herein,urea is chosen as precursor of small molecules or ions to simultaneously engineer the phase (～ 16.4％,～ 69.4％,and ～ 90.2％ of 1T phase) and size (～ 98.8,～ 151.6,and ～ 251.8 nm for the 90.2％ 1T phase) of MoS2 nanosheets,which represent an ideal model system for investigating the structural evolution in these materials,as well as developing a new type of 1T-phase MoS2 arrays.Using reaction intermediate monitoring and theoretical calculations,we show that the oriented growth of 1T-phase MoS2 is controlled by ammonia-assisted assemblly,recrystallization,and stabilization processes.A superior HER performance in acidic media is obtained,with an overpotential of only 76 mV required to achieve a stable current density of 10 mA·cm-2 for 15 h.This excellent performance is attributed to the unique array structure,involving well-dispersed,edge-terminated,and high-purity 1T-phase MoS2 nanosheets.