Water Photolysis by UV Irradiation of Rhodium Loaded Strontium Titanate Catalysts. Relation between Catalytic Activity and Nature of the Deposit from Combined Photolysis and ESCA Studies
Water Photolysis by UV Irradiation of Rhodium Loaded Strontium Titanate Catalysts. Relation between Catalytic Activity and Nature of the Deposit from Combined Photolysis and ESCA Studies
复制标题
载铑钛酸锶催化剂的紫外线照射水光解。
DOI：
10.1002/ijch.198200032
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发表时间：
1982
影响因子：
3.2
通讯作者：
L. Hilaire
中科院分区：
文献类型：
--
作者：
J. Lehn;J. Sauvage;R. Zlessel;L. Hilaire
已经证明，在通过铑物质的表面光沉积改性的钛酸锶水悬浮液的UV照射下发生光化学水分解（H2O H2 + 1/2 O2）。7现在已经使用热沉积技术实现了催化材料的进一步改进。通过在空气中在500°C下加热氯化铑浸渍的SrTiO 3粉末制备的活性最高的材料允许产生可观数量的（H2 + 1/2 O2）气体，并在催化材料上达到高转换数。光解效率呈现出强烈的pH依赖性，在pH = 14附近具有最佳值，并且当光的波长从400 nm减小到300 nm时，光解效率显著增加。沉积的铑的量也具有显著的效果，最佳为约0.2-0.3%重量的铑。ESCA研究提供了关于催化存款的性质及其与材料活性的关系的信息。催化效率和机制方面进行了讨论。铑物种的氧化态有一个剧烈的影响：而SrTiO 3负载还原铑显示没有催化活性，效率增加的渐进氧化的沉积金属表面铑（III）物种，如通过ESCA检测。光活性步骤可以涉及半导体载体的带隙激发和沉积的Rh（III）物质的直接UV激发。
Photochemical water splitting (H2O H2 + 1/2O2) has been shown to occur on UV irradiation of aqueous suspensions of strontium titanate, modified by surface photodeposition of rhodium species.7 Further improvement of the catalytic materials has now been achieved, using thermal deposition techniques. The most active material, prepared by heating rhodium chloride impregnated SrTiO3 powder at 500°C in air, allowed one to produce appreciable quantities of (H2 + 1/2O2) gas and to reach high turnover numbers on the catalytic material. The photolysis efficiency presents a strong pH dependence with an optimum around pH ∼ 14 and increases markedly when the wavelength of the light decreases from 400 to 300 nm. The amount of rhodium deposited also has a marked effect with an optimum at about 0.2–0.3% Rh by weight. ESCA studies have provided information about the nature of the catalytic deposit and about its relation to the activity of the materials. Catalytic efficiency and mechanistic aspects are discussed. The oxidation state of the rhodium species has a drastic influence: whereas SrTiO3 loaded with reduced rhodium shows no catalytic activity, the efficiency increases on progressive oxidation of the deposited metal to surface rhodium(III) species, as detected by ESCA. The photoactive step may involve both band-gap excitation of the semi-conductor support and direct UV excitation of the deposited Rh(III) species.