In-situ template formation method to synthesize hierarchically porous carbon for electrocatalytic reduction of 4-nitrophenol

Abstract An in-situ template formation method is reported for the synthesis of hierarchically porous carbon (PC), with La and Fe nitrates as template precursors and citric acid as carbon precursor. During the carbonization, La and Fe oxides, originated from the metal nitrates, move together and react with each other to form LaFeO3 particles, serving as hard template of the PC. Thus, three types of pores are generated in the PC through (1) the release of gases, (2) the movement of La and Fe oxides and (3) the etching of LaFeO3 particles. TPD-MS and Zeta potential results indicate that the PC contains mainly surface acidic carboxylic groups. Catalytic tests for electroreduction of 4-nitrophenol show that the PC-c is active for the reaction with reduction potential of −0.445 V and peak current of 108.8 μA, which is 3 times higher than that of the PC-g, due to its larger surface area and especially, the richer surface functional groups, which are the active sites of the reaction.