A novel 2D sulfide gallium heterojunction as a high-performance electrocatalyst for overall water splitting

It is an effective way to split water to produce high-clean hydrogen energy for solving energy crisis in the world. However, overall water splitting is still suffering from high voltage and sluggish kinetics. Herein, we firstly synthesize sulfide gallium heterojunction modified with abundant S vacancies in a one-pot hydrothermal way, showing the low OER overpotential of 345 ​mV with good stability as well as HER overpotential of 209 ​mV at 10 ​mA ​cm−2. Furthermore, we assemble the sulfide gallium heterojunction into cathode and anode for overall water splitting, which possesses a low voltage of 1.43 ​V in an alkaline solution. The density functional theory calculations also reveal that the sulfide gallium heterojunction with S vacancy has narrower band energy gap in sulfide gallium. This designed heterojunction has great potential for being used as a novel electrocatalyst to replace the commercial RuO2//Pt/C system in water splitting field. [Display omitted] •Ga2S3-x/rGO silkworm cocoon structured heterojunction is firstly synthesized.•The S vacancies are introduced by one-pot hydrothermal method.•Ga2S3-x/rGO has many active centers to show OER overpotential of 345 ​mV.•Ga2S3-x/rGO shows only 1.43 ​V of overall water splitting voltage.