Facile hydrothermal synthesis of rare earth phosphate for boosting hydrogen evolution reaction

Abstract

The water electrolysis process has attracted great attention due to the production of high energy density pure hydrogen. However, the involved cell reactions in this process such as hydrogen and oxygen evolution reactions are kinetically sluggish and demands high input energy to accelerate the rate of these reactions. Therefore, the development and application of efficient electrocatalyst is essential for hydrogen evolution reaction (HER) as well as oxygen evolution reaction (OER). In the present work, we have successfully synthesized two rare earth phosphates through the hydrothermal route and used as a catalysts towards HER in an acidic medium. The rare earth phosphate PrPO 4 exhibits better catalytic activity than YPO 4 catalyst. The overpotential of PrPO 4 , YPO 4 and standard Pt/C were found as 147, 484.3 and 58 mV vs. reversible hydrogen electrode, respectively, to reach current density 10 mA·cm −2 and corresponding Tafel slopes were found as 107.58, 118.73 and 80.89 mV decade −1 , respectively in 0.5 M H 2 SO 4 . The catalytic activity of PrPO 4 (472.83 mA·cm −2 ) overcome standard Pt/C (179.60 mA·cm −2 ) at high overpotential 450 mV vs. reversible hydrogen electrode. The prepared PrPO 4 shows efficient electrocatalytic activity towards HER in acidic medium because it possess high BET surface area, large ECSA value and small charge transfer resistance than YPO 4 . • Hydrothermal synthesis of rare earth phosphates and explored HER performance. • As prepared PrPO 4 exhibits good catalytic activity towards HER in 0.5 M H 2 SO 4 . • The overpotential 147 mV to get 10 mA·cm −2 and Tafel slope 107.58 mV decade −1 . • The efficient PrPO 4 followed Volmer-Heyrovsky mechanism for HER.