Hierarchical Porous Activated Carbon from Wheat Bran Agro-Waste: Applications in Carbon Dioxide Capture, Dye Removal, Oxygen and Hydrogen Evolution Reactions

This work reports an efficient method for facile synthesis of hierarchically porous carbon (WB-AC) utilizing wheat bran waste. Obtained carbon showed 2.47 mmol g(-1) CO2 capture capacity with good CO2/N-2 selectivity and 27.35 to 29.90 kJ mol(-1) isosteric heat of adsorption. Rapid removal of MO dye was observed with a capacity of similar to 555 mg g(-1). Moreover, WB-AC demonstrated a good OER activity with 0.35 V low overpotential at 5 mA cm(-2) and a Tafel slope of 115 mV dec(-1). It also exhibited high electrocatalytic HER activity with 57 mV overpotential at 10 mA cm(-2) and a Tafel slope of 82.6 mV dec(-1). The large SSA (757 m(2) g(-1)) and total pore volume (0.3696 cm(3) g(-1)) result from N-2 activation contributing to selective CO2 uptake, high and rapid dye removal capacity and superior electrochemical activity (OER/HER), suggesting the use of WB-AC as cost effective adsorbent and metal free electrocatalyst.