Efficient All‐2D Amorphous Cobalt Sulfide Nanosheets/Multilayered Molybdenum Disulfide Hybrid Heterojunction Catalyst for Electrochemical Hydrogen Evolution

Abstract Hydrogen energy is considered to be a critical environmentally friendly and widely sourced renewable energy source that can be used as an alternative to fossil fuels. At present, the preparation of hydrogen (H 2 ) mainly depends on traditional fossil fuels. In order to achieve sustainable development of environmental protection, great attention has been paid to the preparation of H 2 by electrocatalysis, photocatalysis, and photoelectrochemistry. Here, it is reported for the first time that a novel active catalyst for the hydrogen evolution reaction, consisting of all‐2D amorphous nanosheets/2D crystal layer heterojunction structure and without any noble metal (no precious metals are present in the preparation or measuring), is almost entirely fabricated by laser ablation in liquid (LAL) growth of amorphous cobalt sulfide on the surface of multilayered molybdenum disulfide. In acidic media, the amorphous cobalt sulfide nanosheets/multilayered molybdenum disulfide (a‐CoS/MoS 2 ) catalyst exhibits fast hydrogen evolution kinetics with onset potential of −147 mV and a Tafel slope of 126 mV per decade, which is much better than only the amorphous cobalt sulfide and molybdenum disulfide layer. The high hydrogen evolution activity of the amorphous cobalt sulfide nanosheets/multilayered molybdenum disulfide hybrid is likely due to the unique electrocatalytic synergistic effects between hydrogen evolution‐active amorphous cobalt sulfide nanosheets and layered crystal molybdenum disulfide materials, as well as the much‐increased catalytic sites. This work provides a new general route based on all‐2D amorphous nanosheets/2D crystal structure for designing and preparing novel layered materials with effectively manipulated catalytic properties and active functionality surface.