Metal-Free Catalysts for Oxygen Reduction Reaction

Origin and Perspectives of the Photochemical Activity of Nanoporous Carbons

“…Nonmetal inorganic catalysts have been considered as the best options to eventually replace platinum, aiming to overcome the multiple drawbacks of Pt‐based electrodes, such as methanol cross‐over, CO deactivation, and high cost and scarcity 132. Metal‐free electrocatalysts based on carbon nanomaterials (e.g., graphene, carbon nanotubes, and graphitic carbon nitride) have revealed themselves as interesting materials of an electrocatalytic activity for the ORR, particularly those doped‐carbon nanostructures that show improved electronegativity, due to a synergetic charge transfer effect associated with the dopant and the favored O 2 adsorption on the localized charged sites 132…”

Nanoscale Electrocatalysis of Hydrazine Electro-Oxidation at Blistered Graphite Electrodes

“…7,[10][11][12] Carbon is an attractive proposition, due to the possibility of modification by doping and surface functionalization in a wide variety of ways. [13][14][15] This is particularly true of graphite, which comprises stacked graphene layers with weak van der Waals force present between the layers. 7 While outer sphere redox processes, and some more complex electron-proton coupled processes, occur readily at the basal structure of graphite, [16][17][18][19][20][21] electrocatalytic (bond-breaking) reactions often require additional efforts to promote the electrochemical activity.…”

Carbon-Based Metal-Free Electrocatalysis for Energy Conversion, Energy Storage, and Environmental Protection

“…These renewable energy technologies rely on several important reactions, including oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and CO 2 reduction reaction (CO 2 RR), all of which require catalysts. Currently, metal-based catalysts are widely used but suffering from multiple competitive disadvantages, such as low selectivity, poor durability, and negative environmental impacts [4]. Therefore, the development of earth-abundant, costeffective, stable, and catalytically active metal-free alternatives is highly desirable for application in renewable energy technologies.…”

“…The recent availability of carbon nanomaterials, such as graphene, carbon nanotubes (CNTs), graphite nanoplatelets, and three-dimensional (3D) carbon architectures offer new opportunities for the development of advanced metal-free catalysts [4]. Because of high abundance, high electrical conductivity, structure tunability at the atomic level, high selectivity, strong tolerance to acidic/alkaline conditions, and eco-friendliness [4,5], many nanostructured carbon materials have been developed as metal-free catalysts with impressive electrocatalytic performances for ORR, HER, OER, and/or CO 2 RR, key reactions involved in energy conversion/storage and environmental protection processes [3,[6][7][8][9].…”

“…Because of high abundance, high electrical conductivity, structure tunability at the atomic level, high selectivity, strong tolerance to acidic/alkaline conditions, and eco-friendliness [4,5], many nanostructured carbon materials have been developed as metal-free catalysts with impressive electrocatalytic performances for ORR, HER, OER, and/or CO 2 RR, key reactions involved in energy conversion/storage and environmental protection processes [3,[6][7][8][9]. The electrocatalytic performances of metal-free carbon-based catalysts were further found to be tuneable through the regulation of the nanoparticles size, macrostructures, and electrode architectures, along with the introduction of heteroatoms (doping) and defects [8,9].…”