The role of adsorbates in the electrochemical oxidation of ammonia on noble and transition metal electrodes
The role of adsorbates in the electrochemical oxidation of ammonia on noble and transition metal electrodes
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DOI：
10.1016/s0022-0728(01)00491-0
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发表时间：
2001-06-29
影响因子：
4.5
通讯作者：
van Veen, JAR
中科院分区：
文献类型：
--
作者：
de Vooys, ACA;Koper, MTM;van Veen, JAR
研究了氨在铂、钯、铑、钌、铱、铜、银和金电极上的氧化活性和反应过程中形成的中间体。选择性氧化为N（2）的活性与表面物质的性质直接相关：如果存在NH（ads）（或NH（2，ads）），则电极具有活性，而当存在N（ads）时，则电极失活。形成NH（ads）或N（ads）的电位取决于金属。N（ads）的吸附强度的趋势为Ru > Ph > Pd > Ir > Pt，远大于Au、Ag、Cu。这一趋势与在计算的氮原子吸附热中观察到的趋势一致，但铱是个例外。铂是该反应的最佳催化剂，因为与铑和钯相比，N（ads）在高电位下形成，但似乎相当好地稳定NH（ads）。金、银和铜不形成NH（ads）或N（ads），并且仅在表面被氧化时显示活性。在这些条件下，氨增强了金属的电溶解。大多数金属在表面被氧化的电位下会产生含氧产物，如NO和N（2）O。(C)2001 Elsevier Science B.V.保留所有权利。
The activity for ammonia oxidation and the intermediates formed during the reaction have been studied on platinum, palladium, rhodium, ruthenium, iridium, copper, silver and gold electrodes. The activity in the selective oxidation to N(2) is related directly to the nature of the species at the surface: the electrode is active if NH(ads) (or NH(2,ads)) is present and deactivates when N(ads) is present. The potential at which NH(ads) or N(ads) is formed is metal dependent. The observed trend in the strength of adsorption of N(ads) is Ru > Ph > Pd > Ir > Pt much greater than Au, Ag, Cu. This trend corresponds well with the trend observed in the calculated heat of adsorption of atomic nitrogen, with iridium being an exception. Platinum is the best catalyst for this reaction because N(ads) is formed at high potential, compared to rhodium and palladium, but seems to stabilize NH(ads) rather well. Gold, silver and copper do not form NH(ads) or N(ads), and show only an activity when the surface becomes oxidized. The metal electrodissolution is enhanced by ammonia under these conditions. Most metals produce oxygen-containing products, like NO and N(2)O, at potentials where the surface becomes oxidized. (C) 2001 Elsevier Science B.V. All rights reserved.