Defects and morphology engineering for constructing VS-Ni3S2@VS-Cu2S nanotube heterojunction arrays toward efficient bifunctional electrocatalyst for overall water splitting

The development of highly active, stable and inexpensive electrocatalysts for hydrogen production by defects and morphology engineering remains a great challenge. Herein, S vacancies-rich Ni3S2@Cu2S nanotube heterojunction arrays were in-situ grown on copper foam (VS-Ni3S2@VS-Cu2S NHAs/CF) for efficient electrocatalytic overall water splitting. With the merits of nanotube arrays and efficient electronic modulation drived by the 0D vacancy defect and 2D heterojunction defect, the resultant VS-Ni3S2@VS-Cu2S NHAs/CF electrocatalyst exhibits excellent electrocatalytic activity with a low overpotential of 47 mV for the hydrogen evolution reaction (HER) at 10 mA cm−2 current density, and 263 mV for the oxygen evolution reaction (OER) at 50 mA cm−2 current density, as well as a cell voltage of 1.48 V at 10 mA cm−2. Moreover, the nanotube heterojunction arrays endows VS-Ni3S2@VS-Cu2S NHAs/CF with outstanding stability in long-term catalytic processes, as confirmed by the continuous chronopotentiometry tests at current densities of 10 mA cm−2 for 100 h.