Nanoporous Graphitic-C₃N₄@Carbon Metal-Free Electrocatalysts for Highly Efficient Oxygen Reduction

Abstract

Based on theoretical prediction, a g-C(3)N(4)@carbon metal-free oxygen reduction reaction (ORR) electrocatalyst was designed and synthesized by uniform incorporation of g-C(3)N(4) into a mesoporous carbon to enhance the electron transfer efficiency of g-C(3)N(4). The resulting g-C(3)N(4)@carbon composite exhibited competitive catalytic activity (11.3 mA cm(-2) kinetic-limiting current density at -0.6 V) and superior methanol tolerance compared to a commercial Pt/C catalyst. Furthermore, it demonstrated significantly higher catalytic efficiency (nearly 100% of four-electron ORR process selectivity) than a Pt/C catalyst. The proposed synthesis route is facile and low-cost, providing a feasible method for the development of highly efficient electrocatalysts.

Hierarchically porous carbons with optimized nitrogen doping as highly active electrocatalysts for oxygen reduction

“…Nitrogen-doped nanostructured carbon materials represent important candidates as metal-free electrocatalysts for ORR because of their unique electronic properties and structural features [18][19][20] . In spite of some significant achievements attained by the careful selection of suitable precursors and the optimization of nanostructuring process 18,[21][22][23][24][25][26][27][28] , the ORR performance of the reported metal-free catalysts is still inferior to the state-of-the-art Pt/C catalyst in terms of half-wave potential and does not yet warrant implementation in real energy conversion/storage devices. To make metal-free catalysts truly competitive with Pt/C, two crucial factors that govern the performance of the carbon-based, metal-free ORR electrocatalysts have to be considered simultaneously: surface functionalities (mainly the doped nitrogen content and type), which determine the intrinsic nature of active sites, namely the turnover frequency (TOF) per active site, and specific surface area and porous structure.…”

“…The prepared catalysts possess a high specific surface area of 1,280 m 2 g À 1 , a hierarchically porous structure with meso/micro multimodal PSD, and an optimized surface functionality with the desired nitrogen doping. These unique structural features lead to the highest ORR activity (half-wave potential of 0.85 V versus reversible hydrogen electrode (RHE) with a low loading of 0.1 mg cm À 2 ) in alkaline media among all reported nitrogendoped carbon catalysts 18,[21][22][23][24][25][26][27][28] . Furthermore, the full-cell (Zn-air battery) performance of the prepared catalyst outperforms the state-of the-art Pt/C catalyst (20 wt% Pt, BASF).…”

Hydrogen evolution by a metal-free electrocatalyst

“…Very recent advances in low-dimensional carbon materials, as metal-free catalysts, have shown their promising future in energyrelated electrocatalytic oxygen reduction and evolution reactions [20][21][22][23] . However, this innovative concept has not been explored yet for one of the most important electrolysis processes, hydrogen evolution, due to the poorly known HER mechanism on such materials.…”

Bioinspired hollow semiconductor nanospheres as photosynthetic nanoparticles

“…The tri-s-triazine ring structure makes the polymer practically inert to chemical attacks (for example, acid, base, oxygen and organic solvents) and provides an appealing electronic structure as well as surface basicity 24 . These properties have already enabled its use for applications in the energy, catalysis and environmental fields, such as water splitting [25][26][27] , oxygen-reduction reactions 28,29 , selective hydrocarbon oxidation 30,31 , carbon dioxide activation 32 and pollutant control 33 . An improvement to these material functions once this earth-abundant organic semiconductor has been fabricated as a hollow nanostructure with controlled dimensions and surface functionalities can be predicted 34,35 .…”