Photocatalytic Performance Of Multi-metal Modified TiO 2 Based On High-throughput Method

Photocatalysis has been extensively studied as a promising environmental remediation technology for a variety of contaminants including biological agents. Ever since TiO₂ was first discovered as photoelectrodes and exhibited a good catalytic degradation performance under UV light, lots of researchers have paid much attention to the investigation of catalytic performance of semiconductor-based TiO₂. Owing to its biological and chemical inertness, yet strong oxidizing power and cost effectiveness, TiO₂ photocatalyst applied in the fields of water splitting, organic degradation has obtained much more achievements. While there were still many limits in the development of TiO₂ photocatalytic technology, which leads to improving photocatalytic efficiency and making good utilization of sunlight thirsting tasks. In particular, TiO₂ catalysts have a low quantum efficiency with relatively wide band gap ?3.20 eV anatase and rutile 3.03 eV?, so only those whose light of radiant energy is greater than the band gap can be utilized to activate the photocatalytic reaction. Therefore, most of the photons in the reaction could not be used. Moreover, electron and hole are easy to recombine. For these reasons, doping or modifying TiO₂ photocatalyst to promote its photocatalytic activity become an urgent task for the popularization and application of heterogeneous photocatalytic technology. The selenides of Ni, Cu, Cd, Ce, In or Y had been reported extensively as photocatalyst materials, exhibiting good photocatalytic performance. We choose selenide-modified TiO₂ nano-particle as target photocatalysts.There were a variety of the materials or their mixtures being synthesized as catalysts. Conventionally, when researchers chose the co-semiconductor, they have to carry experiments based on the existing records or inexact concludes. Consuming lots of manpower and resources, they did screening, optimization, and verification repeatedly, while got little substantial progress. The recent emergence of high-throughput screening technology has fundamentally changed people's thinking mode because of its efficient, sensitive characters and performance of being a one-time detection of large samples. As an alternative pathway, appropriate high-throughput screening technologies are apt to overcome the obstacle and to broaden the sight of researchers. HTS method is opening a promising method for highly efficient discovery and optimization of new catalysts.A high-throughput screening ?HTS? method based on fluorescence imaging ?FI? was applied to evaluate catalytic performance of multi-metal selenides doped TiO₂. Morphology and chemical composition of the selected catalyst was characterized typically by scanning electron microscope ?SEM? and Energy Dispersive Spectrometer ?EDS?.This study consists of the following key aspects:Preparation of microreactor chip with numerous independent microreactors. A microreactor chip of High-throughput was prepared by UV-lithography technique. Thousands of tiny cells ?500*500um?, with a structure of hydrophobic borders and hydrophilic inward, were finally obtained after coating glue, plate burning and developing.Preparation of catalyst library on chip. Variation of the printed pattern reveals the basic metal compositions of catalyst library and provides a analyse basis for catalytic performance of every microreactor. The establishment of the catalyst library was based on the principle of chemical ink jet printing technology. In our experiment, the selenides of six metals, namely Ni, Cu, Cd, Ce, In, Y were incorporated into TiO₂ surface to study the improved catalytic performance. In practice, chemical ink-jet printing technology was reformed to fabricate a catalyst library comprising 1405 combination ratios doping on TiO₂.Running of Two-Dimensional Reactor for photocatalytic degradation experiment. The catalytic reaction ?eosin degradation? was conducted in a 2D reactor, which was specifically designed for our HTS experiment. Owing to the hydrophobicity of the grid lines, the microdroplets by an ultrasonic nebulizer were finally dispersed and stand in hydrophilic grid cell, ensuring the independence of each react-unit. Because of the performance of varied components of catalysts, react-units displayed diverse changes.Fluorescence imaging test was selected to observe fluorescent intensity in every react unit to evaluate its catalytic performance for eosin degradation. To screen out active catalytic units, optical density was measured in all react-units. Through the HTS method,19 highly active doping ratios on TiO₂ catalysts from the 1405 ratios of metal selenide were screened out efficiently. Conventional verification experiments were carried out to test the catalytic performance of three combinations with the highest activityof(Ni_0.37Cu_{0.04Cd0.28Ce0.05In0.15Y0.11}Sex/TiO₂,(Ni_0.33Cu_0.33Cd_0.01Ce_0.25In_0.00Y_0.08) Sex/TiO₂ and (Ni_0.02Cu_0.01Cd_0.02Ce_0.48In_0.39Y_0.08)Sex/TiO₂, respectively. The results indicated the HTS method is highly effective and accurate in assessing the photocatalytic performance of multi-metal doped TiO₂ system.