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摘要
The development of low-cost, high-performance cathode catalysts is critical for practical application of fuel cells. Here, the N, P-doped porous graphene-like carbon with outstanding oxygen reduction reaction (ORR) performance was synthesized by pyrolysis of surplus sludge, which functioned as a self-doped, self-activated, and self-templated precursor by acclimation with continuous feedings of phenol. The results show that the amounts of microorganisms were enriched after acclimation, with increasing contents of N, P, Fe, as well as C atoms. The increasing pyrolysis temperature resulted in the formation of an ordered graphitic structure, however, the excessively high temperature induced the drop in the amounts of the heteroatoms that are doped in the carbon framework. The phenol-acclimated sludge pyrolyzed at 800 ℃(PSC-800) featured a BET surface area as high as 402.4 m2·g-1, which was much higher than that of the raw sludge carbon (SC-800) (262.4 m2·g-1). X-ray photoelectron spectroscopic (XPS) data suggests that the PSC-800 had higher levels of heteroatom doping, which was conductive to the formation of oxygen reduction active sites such as pyridinic nitrogen and graphitic nitrogen. The obtained PSC-800 exhibited excellent ORR activity in alkaline media with the onset potential of 0.93 V, higher than 0.75, 0.87, 0.91, and 0.89 V for PSC-600, PSC-700, PSC-900 and SC-800, respectively. In comparison to the commercial Pt/C catalyst, the PSC-800 showed comparable catalytic activity in terms of the close onset potential, kinetic-limiting current and four-electron transfer process, and higher tolerance to methanol toxicity and superior stability. ? 2019 Chinese Chemical Society.
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