▪ Abstract  This review discusses the preparation, characterization, and application of amorphous porous mixed oxides, a rapidly growing class of materials with wide applications and a huge potential for the tailoring of chemical composition, microstructure, porosity, and surface properties. In contrast to crystalline materials, these amorphous mixed oxides are prepared under mild reaction conditions in ambient atmosphere. An ever-increasing variety of precursors, additives, modifiers, solvents, catalysts, and posttreatment conditions provide ample fine-tuning options. These materials often display properties commonly associated with well-defined crystalline phases. The functional properties of such solids are largely unexplored and provide a tremendous opportunity for the development of new or alternative materials (solids with a function). Here, emphasis is paid to micro- and mesoporous mixed oxides and their catalytic properties. Easy access to these materials is offset by their much more problematic characterization. Microstructure, chemical structure, morphology, and pore sizes often show broad distributions, and materials description cannot compare with the precise data associated with crystalline phases. The facile preparation and accessibility of these materials make them ideally suited for the application of high-throughput technologies (HTT), which dramatically accelerate searches for new materials as well as fine tuning and optimization. HTT also allow investigators for the first time to access and optimize multinary mixed oxides on a realistic timescale.

A combinatorial work flow for the rapid synthesis and testing of thick oxide films for the development of new gas sensors with improved sensitivity and selectivity involves the synthesis and deposition of mixed‐oxide films of variable composition. The library is based on the sol–gel synthesis of mixed oxides on an array of 8×8 interdigitated electrodes. For the characterization of the sensor arrays, test gas sequences and sensor temperatures were varied.

A method of wet chemical synthesis suitable for high throughput and combinatorial applications has been developed for the synthesis of porous resistive thickfilm gas sensors. This method is based on the robot-controlled application of unstable metal oxide suspensions on an array of 64 inter-digital electrodes positioned on an Al 2 O 3 substrate. SnO 2 , WO 3, ZrO 2 , TiO 2 , CeO 2 , In 2 O 3 and Bi 2 O 3 were chosen as base oxides, and were optimised by doping or mixed oxide formation. The parallel synthesis of mixed oxide sensors is illustrated by representative examples. The electrical characteristics and the sensor performance of the films were measured by high-throughput impedance spectroscopy while supplying various test gases (H 2 , CO, NO, NO 2 , propene). Data collection, data mining techniques applied and the best potential sensor materials discovered are presented.

A complete high throughput assembly for the search for electrochemical sensor materials is described. It is a primary screening device, whose sole purpose is to locate most efficiently new materials with potential sensor properties. The set-up consists of a gas tight reactor for the sensor libraries, an IR-camera, a switching multimeter for dc-resistance measurements, a test gas supply array for different test gases, software for control of experimental flow, data recording, data evaluation, data mining and a database. The sensor libraries consist of a ceramic alumina plate with 64 interdigital electrodes and associated contact pads arranged on the outer rim of the library. The materials are deposited on top of the electrodes and calcined before use. The reactor houses 128 spring loaded electrodes for electrochemical monitoring and a sapphire plate for IR-monitoring of materials responses to exposure to test gases. Data are evaluated automatically and stored in a database for visualization and data mining.

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