Porous molybdenum trioxide as a bifunctional electrocatalyst for oxygen and hydrogen evolution.

Abstract Hierarchically porous molybdenum trioxide (MoO 3) electrocatalyst is controllably synthesized by the facile hydrothermal method with the assistance of soft template (polyethylene oxide-polypropylene oxide-polyethylene oxide, P123). The as-prepared porous MoO 3 material works as a highly efficient and bifunctional electrocatalyst for oxygen and hydrogen evolution. In oxygen evolution reaction (OER), the porous MoO 3 electrode shows an overpotential reduction of 52 mV compared with precious RuO 2 , which is also superior to that of commercial MoO 3. Besides, the electrochemical active surface area (ECSA) of porous MoO 3 (2.8 cm2) which is three times higher than that of commercial MoO 3 (0.8 cm2). For hydrogen evolution reaction (HER), porous MoO 3 electrode exhibits a reduction of 113 mV overpotential at −10 mA cm−2 compared with commercial MoO 3. Furthermore, the ECSA value of porous MoO 3 (1.4 cm2) is four times higher than that of commercial MoO 3 (0.3 cm2). The bifunctional MoO 3 material displays Tafel slopes of 0.44 and 0.75 times for OER and HER than those of commercial MoO 3. Besides, bifunctional MoO 3 material exhibits high durability for both reactions in 24 h. Highlights • Bifunctional porous MoO 3 material is controllably synthesized. • Hierarchically porous MoO 3 catalyst efficient for both OER and HER. • It shows much lower overpotential in OER than that of commercial RuO 2 and MoO 3. • Porous MoO 3 shows a smaller Tafel slope than that of commercial MoO 3 in HER. [ABSTRACT FROM AUTHOR]