Recent Advances in Non-Precious Transition Metal/Nitrogen-doped Carbon for Oxygen Reduction Electrocatalysts in PEMFCs

Abstract

The proton exchange membrane fuel cells (PEMFCs) have been considered as promising future energy conversion devices, and have attracted immense scientific attention due to their high efficiency and environmental friendliness. Nevertheless, the practical application of PEMFCs has been seriously restricted by high cost, low earth abundance and the poor poisoning tolerance of the precious Pt-based oxygen reduction reaction (ORR) catalysts. Noble-metal-free transition metal/nitrogen-doped carbon (M–NxC) catalysts have been proven as one of the most promising substitutes for precious metal catalysts, due to their low costs and high catalytic performance. In this review, we summarize the development of M–NxC catalysts, including the previous non-pyrolyzed and pyrolyzed transition metal macrocyclic compounds, and recent developed M–NxC catalysts, among which the Fe–NxC and Co–NxC catalysts have gained our special attention. The possible catalytic active sites of M–NxC catalysts towards the ORR are also analyzed here. This review aims to provide some guidelines towards the design and structural regulation of non-precious M–NxC catalysts via identifying real active sites, and thus, enhancing their ORR electrocatalytic performance.

Proton Exchange Membrane Fuel Cells (PEMFCs): Advances and Challenges

“…The specifications for a fuel cell system consist of establishing the performance, dimension, weight and size, emissions, output power, rapid start-up, and rapid response to changes in load, lifetime, and operability in intense environments and noise, which play an important role in certain applications. Great attention has been paid to replacing platinum group metals with carbon-based non-precious metal, nanoporous metals [ 333 , 334 , 335 ], heteroatom-doped carbons [ 336 ], covalent organic frameworks [ 337 , 338 ], non-precious metal, or precious-metal-free catalysts of inexpensive metals [ 339 , 340 , 341 ] as a promising new generation of electrocatalysts has emerged. This is due to their reduced cost, enhanced performance, and high stability and activity of fuel cell applications.…”

Catalysts for Oxygen Reduction Reaction in the Polymer Electrolyte Membrane Fuel Cells: A Brief Review

“…The NPMCs are based on transition metals dispersed on nitrogen-doped carbon [70,71]. Generally, the structure of NPMCs can be expressed as M − N (2 or 4) − C, where M denotes the transition metal [72]. The typical structure is depicted in Figure 3b, the metal atom is coordinated into four nitrogen atoms (metal chelate).…”

Influence of Magnetic Moment on Single Atom Catalytic Activation Energy Barriers

“…Many investigations have focused on the role of the relationship between electronic charge transfer and catalytic energy barriers [12,[14][15][16][17][18]. Recent work has shown that magnetic moment also plays a role in the catalytic reactivity of O 2 , which is unusually stable with a triplet ground state [19]. Distinguishing the effects of spin state from more traditionally investigated mechanisms such as charge transfer requires understanding the spin polarized density of states of SAC environments, which is most readily accessible with a first principles approach.…”