To achieve an efficient conversion of renewable energy sources through water splitting, low-cost, efficient, and eco-friendly catalysts are required for oxygen and hydrogen evolution. Here, we develop a vertically aligned cobalt molybdenum sulfide (CoMoS) nanosheets on a conductive polyaniline (PANI) nanowire on nickel foam (NF) by a one-step solvothermal synthesis. The macroporous nickel foam improve the carry of the O2 gas evolved, and vertically aligned CoMoS nanosheets on a three-dimensional PANI nanowire substrate form a hybrid architecture, promoting electrolyte penetration and the removal of gas bubbles, enabling firm touch between reactants and active sites, and generating smooth pathways for effective charge transport in the conductive channels. The hybrid CoMoS-PANI requires only 250 and 98 mV, to achieve a current density of 10 mA cm–2 in 1 M KOH, for the oxygen and hydrogen evolution reactions, respectively. As an electrode for overall water splitting, CoMoS-PANI/NF, as both the anode and the cathode, shows a current density of 10 mA cm–2 at a low cell voltage, 1.58 V. Moreover, it possessed excellent durability during the 50 h stability test, suggests that CoMoS-PANI is an efficient and stable bifunctional catalyst. The upgraded electrocatalytic activity of CoMoS-PANI can be attributed to the synergistic interaction between Co, Mo, S, and PANI. First, the CoMoS nanosheets were grown on conductive PANI nanowire substrate as hybrid architectures, encouraging electrolyte piercing and the removal of gases, enabling strong contact between and reactants and active sites, and creating a smooth pathway for effective charge transportion. Second, the defect rich structure, S vacancies centered in the CoMoS nanosheet structure, and amines in the PANI nanowire create a high electrochemically active surface area and a large number of active sites, expose active interfaces, and maintain the conductivity. Finally, the effective inter-electron transfer between cobalt and molybdenum and the intra-electron transfer between PANI and CoMoS reduce the kinetic energy barrier of initial water dissociation and ion adsorption. Thus, these factors resulted in excellent augmented performance for OER, HER, and overall water splitting. This work creates a promising step towards the synthesis of hybrid materials as excellent electrocatalysts for renewable energy generation.
Dr. Sobin Mathew is Ph.D research fellow in Pusan National University, Division of Material science and engineering
Topics : Hybrid Materials, Water splitting, Electrochemistry, Hydrogen Fuel Cell.