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In this work,a simple and efficient microfluidic chip-based system for rapid screening of photocatalysts was developed.A new microfluidic introduction method for solid particle samples was established to load different photocatalysts into the chip channels.Using the chip with multi-channel array,ten photocatalysts reactions were achieved within 15 min.High reaction rate in chip microreactors was obtained with an increase of two orders of magnitude over bulk reactors.The catalyst screening system consisted of a microchip with multiple channels for parallel reactions,a UV light source,and a CCD camera for monitoring the photocatalytic reaction.The microchip with a wedge structure in each channel was fabricated using standard photolithographic and wet etching technique.The substrate with a shallow channel (15 μm depth) and the substrate with a deep channel (100 μm) were aligned and then bonded together using room-temperature prebonding and high-temperature (560 °C) bonding techniques.In this work,a novel microfluidic introduction method for solid particle samples was used to load photocatalysts into microchannels with wedge microstructures to form catalyst columns.A syringe was connected with the inlet of the channel via a pipette tip.First the syringe was filled with catalyst particles.Then the pipette tip was inserted into the inlet,and the catalyst particles were pushed into the channel.The catalyst particles were introduced into the channel with a syringe,and blocked by the wedge structure forming a catalyst column.Another syringe filled with methylene blue (MB) solution was used to drive the dye solution to enter the column.A 120-W Xe lamp was used as light source to irradiate the column region.A stereoscopic microscope coupled with a CCD camera was used to observe the photocatalytic reaction.The captured CCD images were analyzed by ImageJ software.The catalytic performances of various doped TiO2 photocatalysts were evaluated in terms of their activity for methylene blue degradation under UV light irradiation (Fig.2).As shown in Fig.2,the catalysts prepared by doping K+,Ca2+ did not improve the catalytic activity of TiO2.It is also apparent that doping Co3+ or Mo6+ did not have any positive effect on the catalytic activities of TiO2 materials.However,doping TiO2 with F-,Si4+,Au0 obviously enhanced their corresponding catalytic activities.The F-doped TiO2 catalysts showed the best catalytic performance in the MB photodegradation.