Nalajala Naresh, Patra Kshirodra Kumar, Bharad Pradnya A, Gopinath Chinnakonda S
Catalysis Division, National Chemical Laboratory Dr Homi Bhabha Road Pune 411 008 India
Centre of Excellence on Surface Science, National Chemical Laboratory Dr Homi Bhabha Road Pune 411 008 India.
RSC Adv. 2019 Feb 19;9(11):6094-6100. doi: 10.1039/c8ra09982k. eCollection 2019 Feb 18.
We demonstrated an easy method to improve the efficiency of photocatalysts by an order of magnitude by maximizing light absorption and charge carrier diffusion. Degussa titania (P25) and Pd/P25 composite photocatalyst thin films coated over regular glass plates were prepared and evaluated for solar hydrogen production in direct sunlight with aqueous methanol. It is worth noting that only UV light present in direct sunlight (∼4%) was absorbed by the catalysts. The hydrogen production activities of catalysts were compared for thin film and particulate forms at 1 and 25 mg levels. The hydrogen yield values suggested that 1 mg thin film form of Pd/P25 provided 11-12 times higher activity than 25 mg powder form. Comparable light absorption throughout the entire thickness of photocatalyst device and better contact of nanostructures that enabled the charge diffusion and charge utilization at redox sites are the reasons for high efficiency. While solar cells require charge carriers to diffuse through long distances of microns, they are utilized locally in an ensemble of particles (of nanometres) for hydrogen generation in photocatalyst thin films; this concept was used effectively in the present work.
我们展示了一种简单的方法，通过最大化光吸收和电荷载流子扩散，将光催化剂的效率提高一个数量级。制备了涂覆在普通玻璃板上的德固赛二氧化钛（P25）和Pd/P25复合光催化剂薄膜，并在直射阳光下用甲醇水溶液对其太阳能制氢性能进行了评估。值得注意的是，催化剂仅吸收直射阳光中存在的紫外光（约4%）。比较了1毫克和25毫克水平下薄膜和颗粒形式催化剂的产氢活性。产氢量值表明，1毫克薄膜形式的Pd/P25比25毫克粉末形式的活性高11至12倍。光催化剂装置整个厚度上可比的光吸收以及纳米结构之间更好的接触，使得电荷能够在氧化还原位点扩散和利用，这就是高效的原因。虽然太阳能电池需要电荷载流子扩散很长的微米距离，但在光催化剂薄膜中，它们在一组（纳米级）颗粒中局部用于产氢；这一概念在本工作中得到了有效应用。
