Developing a low cost, highly active and durable cathode material is a high-priority research direction toward the commercialization of low-temperature fuel cells. However, the high cost and low stability of useable materials remain a considerable challenge for the widespread adoption of fuel cell energy conversion devices. The electrochemical performance of fuel cells is still largely hindered by the high loading of noble metal catalyst (Pt/Pt alloy) at the cathode, which is necessary to facilitate the inherently sluggish oxygen reduction reaction (ORR). Under these circumstances, the exploration of alternatives to replace expensive Pt-alloy for constructing highly efficient non-noble metal catalysts has been studied intensively and received great interest. Metal–organic frameworks (MOFs) a novel type of porous crystalline materials, have revealed potential application in the field of clean energy and demonstrated a number of advantages owing to their accessible high surface area, permanent porosity, and abundant metal/organic species. Recently, newly emerging MOFs materials have been used as templates and/or precursors to fabricate porous carbon and related functional nanomaterials, which exhibit excellent catalytic activities toward ORR or oxygen evolution reaction (OER). In this review, recent advances in the use of MOF-derived functional nanomaterials as efficient electrocatalysts in fuel cells are summarized. Particularly, we focus on the rational design and synthesis of highly active and stable porous carbon-based electrocatalysts with various nanostructures by using the advantages of MOFs precursors. Finally, further understanding and development, future trends, and prospects of advanced MOF-derived nanomaterials for more promising applications of clean energy are presented.
Developing an economical, highly active and durable material to replace the conventional, expensive noble metal electrocatalyst is an important milestone in the development of fuel cell technology. Nanocarbon materials are considered as promising catalysts toward the oxygen reduction reaction (ORR) in fuel cells, due to their reasonable balance between low-cost, long-life durability and high catalytic activity in alkaline media. In this work, we present the fabrication of N,S-co-doped nanocarbon derived from a metal-organic framework (MOF) precursor for use as an electrocatalyst towards ORR. High resolution transmission electron microscopy (HRTEM) mapping demonstrates the uniform distribution of N and S atoms into the nanocarbon skeleton. The nitrogen absorption–desorption isotherms indicate that the MOF-derived N,S-co-doped nanocarbon has a high specific surface area (2439.9 m2 g−1) and a porous structure. Importantly, the N,S-co-doped nanocarbon exhibits higher catalytic activity toward ORR, better long-term stability and methanol tolerance than commercial Pt/C catalyst. First-principles calculations demonstrate that the remarkable electrochemical properties of N,S-co-doped nanocarbon are mainly attributed to the synergistic effect from the N and S dopants. Moreover, for the first time, it is revealed that the N,S-coupled dopants in nanocarbon can create active sites with higher catalytic activity for ORR than the isolated N and S-dopants. This finding on the structure–performance relationship of the co-doped nanocarbon provides guidelines for the design of high performance electrocatalysts.
The development of highly efficient electrocatalysts toward the oxygen evolution reaction is imperative for advancing water splitting technology to generate clean hydrogen energy. Herein, a two dimensional (2D) nanosheet ammonium cobalt phosphate hydrate (NH4CoPO4·H2O) catalyst based on the earth‐abundant non‐noble metal is reported. When used for the challenging alkaline saline water electrolysis, the NH4CoPO4·H2O catalyst with the optimal thickness of 30 nm achieves current densities of 10 and 100 mA cm−2 at the record low overpotentials of 252 and 268 mV, respectively, while maintaining remarkable stability during the alkaline saline water oxidation at room temperature. X‐ray absorption fine spectra reveal that the activation of Co (II) ions (in NH4CoPO4·H2O) to Co (III) species constructs the electrocatalytic active sites. The 2D nanosheet morphology of NH4CoPO4·H2O provides a larger active surface area and more surface‐exposed active sites, which enable the nanosheet catalyst to facilitate the alkaline freshwater and simulated seawater oxidation with excellent activity. The facile and environmentally‐benign H2O‐mediated synthesis route under mild condition makes NH4CoPO4·H2O catalyst highly feasible for practical manufacturing. In comparison with noble metals, this novel electrocatalyst offers a cost‐effective alternative for economic saline water oxidation to advance water electrolysis technology.