Designing of transition metal dichalcogenides based different shaped trifunctional electrocatalyst through adjourn-reaction scheme

In this article, for the first time, we have designed a new reaction mechanism i.e. adjourned-reaction to fabricate shape specific transition metal dichalcogenides based electrocatalyst. Herein, the MoSe2/MoO3 and WSe2/WO3 based different shaped nanohybrids were prepared in a new, economic and creative way by adjourning the complete 24 h hydrothermal reaction for 30 min at an interval of 3 h. By optimizing the temperature and adjourning time different shape of MoSe2/MoO3 and WSe2/WO3 were prepared and from them four specific shapes nanohybrids i.e. MoSe2/MoO3-1 (150 degrees C) Marigold like flower, MoSe2/MoO3-2 (200 degrees C) thin rod agglomerated flower, WSe2/WO3-1 (150 degrees C) rhombic dodecahedron, WSe2/WO3-2 (200 degrees C) nanorod, were selected to explore their trifunctional electrocatalytic activity towards oxygen reduction, oxygen evolution and hydrogen evolution reactions (OER, ORR, HER). The shape-specific trifunctional electrochemical study was performed over the prepared nanohybrids and it was observed that flower-shaped MoSe2/MoO3-2 nanohybrid having thin and small rod-like petals shows the best performances with smallest OER onset potential=1.1 V, high current density=350 mA cm(-2) and small OER Tafel slope of 45 mV/dec. The prepared catalyst also shows very good ORR property with more positive onset potential of 930 mV and Tafel slope of 32 mV/dec. Beside OER and ORR the catalyst shows good HER behavior, due to its small thread like active hydrogen evolution site and exhibit very low onset potential of -0.085 V with low overpotential value of 270 mV and low Tafel slope of 27 mV/dec. The prepared catalyst is free from any methanol cross-over effect and shows good durability and stability, under various extreme conditions. In addition, MoSe2/MoO3-2 based zinc-air battery has also been prepared, which shows an outstanding performance and proves their potential for energy storage and conversion based devices.