Non-noble electrocatalysts for O2 reduction:: How does heat treatment affect their activity and structure?: Part I.: Model for carbon black gasification by NH3:: Parametric calibration and electrochemical validation
Non-noble electrocatalysts for O2 reduction:: How does heat treatment affect their activity and structure?: Part I.: Model for carbon black gasification by NH3:: Parametric calibration and electrochemical validation
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DOI：
10.1021/jp068273p
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发表时间：
2007-04-26
影响因子：
3.7
通讯作者：
Dodelet, Jean-Pol
中科院分区：
文献类型：
--
作者：
Jaouen, Frederic;Dodelet, Jean-Pol
在本文的第一部分中，开发了NH3气化原始炭黑的模型。在这里，它是适用于调查非贵金属催化剂的O-2还原反应（ORR）在燃料电池。这些催化剂通过在NH3中热解负载有0.2重量% Fe的炉黑来制备。该模型预测（i）初始无孔的炉黑颗粒的气化速率和（ii）由此产生的内部多孔网络。该模型假设两个速率常数的炭黑的气化：一个石墨微晶和一个无序的基质相。该模型适合于（i）炭黑的重量损失和（ii）在用于ORR的非贵金属催化剂的合成期间测量的比表面积的实验时间演变。拟合产生的速率常数是十倍大的气化的无序相比石墨相。对于42 nm直径的颗粒，该模型预测（i）气体-碳反应，以及因此内部多孔网络，发生在厚度为40%的外壳中。
In part I of this paper, a model for the gasification of pristine carbon blacks by NH3 is developed. Here, it is applied to investigate non-noble catalysts for the O-2 reduction reaction (ORR) in fuel cells. These catalysts are produced by pyrolyzing a furnace black, loaded with 0.2 wt % Fe, in NH3. The model predicts (i) the gasification rate of an initially pore-free particle of furnace black and (ii) the internal porous network thereby created. The model assumes two rate constants for the gasification of carbon black: one for the graphitic crystallites and one for the disordered matrix phase. The model is fitted to experimental time-evolutions of (i) weight loss of carbon black and (ii) specific surface area measured during the synthesis of non-noble catalysts for the ORR. The fittings yield a rate constant that is ten times larger for the gasification of the disordered phase than that for the graphitic phase. For a 42 nm diameter particle, the model predicts that (i) the gas-carbon reaction, and therefore the internal porous network, occurs in an outer shell of thickness 40%).