A No-Sweat Strategy for Graphene-Macrocycle Co-assembled Electrocatalyst toward Oxygen Reduction and Ambient Ammonia Synthesis.

Abstract

Toward the realm of sustainable energy, the development of efficient methods to enhance the performance of electrocatalysts with molecular level perception has gained immense attention. Inspite of untiring attempts, the production cost and scaling-up issues have been a step back toward the commercialization of the electrocatalysts. Herein, we report a one-pot electrophoretic exfoliation technique with minimum time and power input to synthesize iron phthalocyanine functionalized high-quality graphene sheets (G-FePc). The π-stacked co-assembly excels in oxygen reduction performance (major criterion for fuel cells) with a high positive E1/2 of 0.91 V (vs RHE) and a reproducible reduction peak potential of 0.90 V (vs RHE). An overpotential as low as 29 mV dec-1 and complete tolerance toward the methanol crossover effect confirm the authentication of the catalytic performance of our designed catalyst G-FePc. The catalyst simultaneously exhibits hydrogen storage efficacy by means of nitrogen fixation, yielding 27.74 μg h-1 mgcat-1 NH3 at a potential of -0.3 V (vs RHE) in an acidic electrolyte. The structure-function relationship of the catalyst is revealed via molecular orbital chemistry for the bonding of the Fe(II) active center with O2 and N2 during catalysis.