Phosphorus doping and heat transformation trigger controllable MoS2/MoO2 heterojunction construction and defects optimization for efficient overall water splitting

Exploring low-cost and highly efficient electrocatalysts with bifunctional activities of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is practically essential for overall water splitting. Nevertheless, perfectly balancing the catalytic behavior between HER and OER continues to be a great challenge due to their distinct conducting behaviors and free energies. Herein, an advanced bifunctional electrocatalyst based on P-doped defective MoS 2 /MoO 2 heterostructure integrated onto highly conductive carbon cloth has been constructed for overall water splitting in acidic media. By reasonably controlling reaction conditions, the MoS 2 /MoO 2 heterostructure can be rationally constructed and the corresponding sulfur vacancies can be well optimized. Meanwhile, the abundant oxygen vacancies can be also created during the heat transformation processes. Benefiting from the unique structural features that favor the active species adsorption and electron transfer, the resultant A-P-M-3/CC catalyst exhibits exceptional bifunctional electrocatalytic activity, with low overpotentials of 67 and 104 mV at 10 mA cm −2 for HER and OER, respectively. When coupled in a two-electrode electrolyzer, A-P-M-3/CC delivers 10 mA cm −2  at a low cell voltage of 1.44 V with good stability, surpassing most of similar electrocatalysts. This work offers a novel avenue for water splitting catalyst optimization.