Hierarchical exfoliated MoS2@Ti3C2T x @α-Ni(OH)2 as a highly efficient electrocatalyst for water splitting in acidic medium: experimental and DFT investigations.

The development of efficient bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is critical for advancing renewable energy technologies. In this work, we design and synthesize a hierarchical exfoliated exfMoS2@Ti3C2T x @α-Ni(OH)2 heterostructure that functions as a highly active bifunctional electrocatalyst under acidic conditions. The catalyst exhibits excellent catalytic activity for electrochemical water splitting, delivering low overpotentials of 127 mV for the HER and 280 mV for the OER at a current density of 10 mA cm-2 in 0.5 M H2SO4. Furthermore, a symmetric H-cell device using exfMoS2@Ti3C2T x @α-Ni(OH)2∥exfMoS2@Ti3C2T x @α-Ni(OH)2 electrodes achieves an overall water splitting voltage of 1.61 V to reach 10 mA cm-2 with robust stability over 72 h of continuous performance. Density functional theory (DFT) calculations, combined with Gibbs free energy analyses, reveal the electronic band structures of the exfMoS2@Ti3C2T x @α-Ni(OH)2 heterostructure and corroborate its enhanced catalytic activity. The synergistic integration of exfMoS2, Ti3C2T x , and α-Ni(OH)2 promotes efficient charge transfer, optimizes hydrogen and oxygen intermediate adsorption, and accelerates reaction kinetics. This study demonstrates the potential of exfMoS2@Ti3C2T x @α-Ni(OH)2 as an efficient bifunctional electrocatalyst for the HER, the OER, and overall water splitting and provides mechanistic insights into the electrochemical processes involved.