Towards high-efficiency nanoelectrocatalysts for oxygen reduction through engineering advanced carbon nanomaterials

Abstract

One of the critical issues in the industrial development of fuel cells (e.g., proton exchange membrane fuel cells, direct methanol fuel cells and biofuel cells) is the high cost, serious intermediate tolerance, anode crossover, sluggish kinetics, and poor stability of the platinum (Pt) as the preferred electrocatalysts for the oxygen reduction reaction (ORR) at the cathode. The development of novel noble-metal-free electrocatalysts with low cost, high activity and practical durability for ORR has been considered as one of the most active and competitive fields in chemistry and materials science. In this critical review, we will summarize recent advances on engineering advanced carbon nanomaterials with different dimensions for the rational design and synthesis of noble-metal-free oxygen reduction electrocatalysts including heteroatom-doped carbon nanomaterials, transition metal-based nanoparticle (NP)-carbon nanomaterial composites and especially the stable iron carbide (Fe3C)-based NP-carbon nanomaterial composites. Introducing advanced carbon nanomaterials with high specific surface area and stable structure into the noble-metal-free ORR field has not only led to a maximized electrocatalyst surface area for the electron transfer but also resulted in enhanced electrocatalyst stability for long-term operation. Therefore, the rational design and synthesis of noble-metal-free electrocatalysts based on heteroatoms, transition metal-based NPs and Fe3C-based NP functionalized carbon nanomaterials are of special relevance for their ORR applications, and represents a rapidly growing branch of research. The demonstrated examples in this review will open new directions on designing and optimizing advanced carbon nanomaterials for the development of extremely active and durable earth-abundant cathodic catalysts for fuel cell applications.

Hierarchically porous Fe–N–C derived from covalent-organic materials as a highly efficient electrocatalyst for oxygen reduction

“…[1][2][3] Over the past decades, tremendous efforts have been made to overcome this problem, including nonnoble metal complexes, 4 metal oxides, 5 metal alloys, 6 and metalfree heteroatom-doped carbons. 7 In particular, transition metalnitrogen decorated carbons (M-N-C, M: Fe, Co, Ni, etc.)…”

Three-Dimensional Heteroatom-Doped Nanocarbon for Metal-Free Oxygen Reduction Electrocatalysis: A Review

“…Additionally, the tailorable surface chemistry, abundant structural variety, and low cost of nanocarbons together boost their harvesting as active catalysts for ORR in metal-air batteries and fuel cells [22,34]. Nevertheless, structure optimization of nanocarbon catalysts is one of the main strategies to sufficiently expose and/or activate the catalytic sites.…”

“…Over the past decade, carbon-based metal-free electrocatalysts doped with heteroatom, such as N, S, B, P, and their mixtures, have emerged as front runners to replace Pt and other noble metals for highly efficient ORR [22,54]. Both experiments and theoretical calculations show that the doping of heteroatoms in the sp 2 lattice of graphitic carbon can alter the electronic arrangement of the carbon-based material and tailor their electron donor properties, as a result, breaking the electroneutrality of sp 2 carbon to create charged sites favorable for O 2 adsorption and enhancing effective utilization of carbon π electrons for O 2 reduction, thus leading to improved ORR electrocatalytic activity [24,29,43].…”

Facile synthesis of mesoporous carbon material from treated kitchen waste for energy applications

“…However, it is a costlier metal, and another major issue associated with it is the CO poisoning which degrades the operational stability of an FC [10]. A recent breakthrough in this direction is the use of porous carbon material (PCM) (synthesized using biomass materials) based cathode electrocatalysts to fasten the rate of ORR [11,12]. Sun et al [13] synthesized high surface area (1177.76 m 2 g −1 ) PCM by carbonizing waste cornstalks at 1000 °C.…”