Oxygen photoevolution on a tantalum oxynitride photocatalyst under visible-light irradiation: how does water photooxidation proceed on a metal-oxynitride surface?
Oxygen photoevolution on a tantalum oxynitride photocatalyst under visible-light irradiation: how does water photooxidation proceed on a metal-oxynitride surface?
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DOI：
10.1021/jp0501289
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发表时间：
2005-03
期刊：
影响因子：
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通讯作者：
Ryuhei Nakamura;Tomoaki Tanaka;Y. Nakato
中科院分区：
文献类型：
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作者：
Ryuhei Nakamura;Tomoaki Tanaka;Y. Nakato
在前期对TiO(2)和N掺杂TiO(2)光催化水光氧化反应机理研究的基础上，研究了TaON光催化剂上水光氧化反应（氧光分解）的机理。正如报道的那样，我们已经证实，在 Fe(3+) 存在的情况下，TaON 水悬浮液会产生光催化 O(2) 析出。原位MIR-IR实验表明，TaON表面在可见光照射下轻微氧化，表明TaON上的氧光演化实际上发生在薄薄的Ta氧化物覆盖层上。原位MIR-IR实验还表明，某些表面过氧物种（暂定为吸附的HOOH）是作为O(2)光演化反应的中间体形成的。电解液中添加还原剂对IPCE影响的研究表明，TaON表面的光生空穴不能氧化SCN(-)、Br(-)、甲醇、乙醇、2-丙醇和乙酸等还原剂，但可以将H(2)O氧化成O(2)。对这些结果的详细考虑强烈表明，TaON上的水光氧化反应是通过我们最近提出的新机制进行的，即该反应是由水分子（路易斯碱）对表面捕获的空穴（路易斯酸）的亲核攻击引发的。
The mechanism of water photooxidation (oxygen photoevolution) on a TaON photocatalyst was studied on the basis of our previous studies on the mechanism of this reaction on TiO(2) and N-doped TiO(2). We have confirmed that photocatalytic O(2) evolution occurs from an aqueous TaON suspension in the presence of Fe(3+), as reported. In-situ MIR-IR experiments have indicated that the TaON surface is slightly oxidized under visible-light irradiation, indicating that the oxygen photoevolution on TaON actually occurs on a thin Ta-oxide overlayer. The in-situ MIR-IR experiments have also shown that a certain surface peroxo species, tentatively assigned to adsorbed HOOH, is formed as an intermediate of the O(2) photoevolution reaction. Studies on the effect of addition of reductants to the electrolyte on the IPCE have shown that photogenerated holes at the TaON surface cannot oxidize reductants such as SCN(-), Br(-), methanol, ethanol, 2-propanol, and acetic acid, though they can oxidize H(2)O into O(2). Detailed considerations of these results have strongly suggested that the water photooxidation reaction on TaON proceeds by our recently proposed new mechanism, that is, the reaction is initiated by a nucleophilic attack of a water molecule (Lewis base) on a surface-trapped hole (Lewis acid).