Role of oxygen vacancies in catalytic SO3 decomposition over Cu2V2O7 in solar thermochemical water splitting cycles
Role of oxygen vacancies in catalytic SO3 decomposition over Cu2V2O7 in solar thermochemical water splitting cycles
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DOI：
10.1021/jp410431a
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发表时间：
2013-12
影响因子：
3.7
通讯作者：
M. Machida;T. Kawada;Hiroaki Yamashita;Tonami Tajiri
中科院分区：
文献类型：
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作者：
M. Machida;T. Kawada;Hiroaki Yamashita;Tonami Tajiri
本文报道了焦钒酸铜（Cu_2V_2O_7）在太阳能热化学水分解循环中作为一种有效的SO_3分解催化剂的构效关系。在Cu 2 V2 O 7的α、β和γ多晶型中，具有钙钛矿型结构的α相在催化反应条件下是稳定的。在600 °C下，伴随着通过将Cu 2+还原为Cu+的电荷补偿的自发氧解吸产生对应于Cu 16 V 16 O 55的氧缺乏。基于这些结果的密度泛函理论计算表明，氧空位的形成是更有利的Cu-O-V桥接网站比V-O-V网站的焦钒酸盐单元。（100）面的氧空位形成能远小于体相Cu_（16）V_（16）O_（56）的氧空位形成能。Cu 16 V16 O 55 + SO 3 → Cu 16 V16 O 56 + SO2反应是放热反应，表明氧空位在Cu 2 V2 O 7催化剂上SO 3催化分解中起关键作用。
We report the structure–activity relationship of copper pyrovanadate (Cu2V2O7) as an efficient catalyst for SO3 decomposition in solar thermochemical water splitting cycles. Of the α, β, and γ polymorphs of Cu2V2O7, the α-phase, which has a blossite-type structure, was stable under the catalytic reaction conditions. Spontaneous oxygen desorption accompanied by charge compensation through the reduction of Cu2+ to Cu+ produced an oxygen deficiency corresponding to Cu16V16O55 at 600 °C. Density functional theory calculations based on these results showed that oxygen vacancy formation is more favorable on the Cu–O–V bridging sites than on the V–O–V site in the pyrovanadate unit. The oxygen vacancy formation energy of the (100) surface is considerably less than that of bulk Cu16V16O56. The reaction, Cu16V16O55 + SO3 → Cu16V16O56 + SO2, is exothermic, suggesting that oxygen vacancies play a key role in catalytic SO3 decomposition over a Cu2V2O7 catalyst.