Two-dimensional double transition metal carbides as superior bifunctional electrocatalysts for overall water splitting

Abstract

The development of bifunctional catalysts that can outperform precious metal electrocatalysts for overall water splitting is a critical task for sustainable green hydrogen production. Owing to the rich surface chemistry, unique physiochemical properties, and good stability, MXenes are considered efficient catalysts for hydrogen production. However, it is still a challenge to harmonize both HER (Hydrogen evolution reaction) & OER (Oxygen evolution reaction) reactions in the same media. Herein, we have reported the synthesis of Mo2TiC2Tx and Mo2Ti2C3Tx double transition metal carbides as NMP (non-precious metal) based bifunctional catalysts for overall water splitting in alkaline media. The LSV (linear sweep voltammetry) was employed for investigating catalytic activity, revealing the outstanding performance of Mo2TiC2Tx and Mo2Ti2C3Tx for high HER activity with an overpotential of 34 mV and 51 mV respectively, to reach a benchmark current density of 10 mAcm−2. The Mo2TiC2Tx also exhibited excellent OER activity with an overpotential of 320 mV as compared to 470 mV for Mo2Ti2C3Tx. The overall water splitting test uncovers a cell voltage of 1.57 V for Mo2TiC2Tx \\\\ Mo2TiC2Tx configuration. This study provides a comparison of two double transition MXene systems for effective use as bifunctional catalysts that opens new horizons for their use in clean hydrogen production.