Aqueous phase photocatalytic nitrate destruction using titania based materials: routes to enhanced performance and prospects for visible light activation

Mikaela Shand; James A. Anderson

摘要

Use of titania based photocatalysts for the selective reduction of nitrates to nitrogen through photocatalytic methods has attracted some interest in recent years and the need to operate this process remotely and without energy sources will ensure that a level of interest will remain in attempting to improve this process. There remain numerous avenues that have not yet been investigated in the effort to optimise a catalyst for this reaction. Work on metal containing systems offer the potential to; improve activity through offering a route to improved electron-hole separation, manipulate selectivity by controlling particle size which affects the flat band potential under Fermi equilibration conditions and for operation in the visible region by manipulating particle shape and using SPR properties. Opportunities to further manipulate all three of these situations by using bimetallic particles using core-shell, true alloy and other forms, remains open for exploration. The introduction of hetero-species into bulk titania in order to reduce the band gap and permit operation within the visible region. The key issues in the case of the reaction involved would be to retain the oxidation potential of the valance band but to sacrifice the reduction potential of the conduction band thus permitting nitrate reduction but avoiding competition for electrons by protons in solution. In a more general approach, the key challenge should be to obtain a route to uniform bulk doping without the need to use complex ion implantation routes. Composites offer the opportunity to manipulate adsorption capacity although as yet, attempts to improve nitrate adsorption with respect to other organic anions has not been attempted. They may also be used to improve electron transfer properties and to enhance charge-carrier lifetimes.

机译：使用基于二钛的光催化剂来选择性地减少硝酸盐通过光催化方法将硝酸盐减少为氮，这引起了近年来的一定兴趣，并且需要远程操作此过程，而无需能源来确保将保持一定的兴趣水平，以改善这一过程，以改善这一过程。在为该反应优化催化剂的努力中，仍有许多尚未研究的途径。在含有金属系统的系统上的工作提供了潜力;通过提供改善电子孔分离的途径来改善活动，通过控制粒径来操纵选择性，从而在费米平衡条件下影响平坦带势并通过操纵粒子形状和使用SPR属性来影响可见区域的平坦带势。通过使用核心壳，True Alloy和其他形式使用双金属颗粒来进一步操纵这三种情况的机会仍然开放供探索。为了减少带隙并允许在可见区域内运行，将异质物种引入散装二钛。涉及反应的关键问题是保留价带的氧化潜力，但要牺牲传导带的还原电位，从而允许硝酸盐减少，但避免了质子在溶液中对电子的竞争。在更通用的方法中，关键的挑战应该是获得一条均匀的散装掺杂途径，而无需使用复杂的离子植入路线。复合材料提供了操纵吸附能力的机会，尽管尚未尝试改善相对于其他有机阴离子的硝酸盐吸附的尝试。它们还可以用来改善电子传输特性并增强电荷载体寿命。

Aqueous phase photocatalytic nitrate destruction using titania based materials: routes to enhanced performance and prospects for visible light activation

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