Recycling waste tantalum capacitors to synthesize high value-added Ta2O5 and polyaniline-decorated Ta2O5 photocatalyst by an integrated chlorination-sintering-chemisorption process

Waste tantalum capacitors, containing about 30–40 wt% rare metal tantalum (Ta), are one of the main Ta secondary resources. Not just to achieve the Ta resource recovery but to realize the value-added utilization, we recycled waste tantalum capacitors to prepare Ta2O5 photocatalyst by a chlorination-sintering process. To enhance the photocatalytic performance, Ta2O5 was further decorated by polyaniline (PANI) through a chemisorption approach. The as-prepared Ta2O5 and Ta2O5/PANI photocatalysts exhibited irregular nanoparticles with the particle size of 50–80 nm. After the PANI decoration, the photocatalytic performance of Ta2O5 was significantly enhanced. The optimal simulated sunlight H2 evolution rate and RhB degradation rate constant of Ta2O5/PANI (3 wt%) could reach 200.8 μmolg−1h−1 and 0.1342 min−1, which were about 3.3 and 5.6 times higher than those of Ta2O5. The superior photocatalytic performance of Ta2O5/PANI was ascribed to the intense interfacial interaction, increased visible light absorption and efficient charge carrier separation. In short, this study demonstrates a sustainable approach to convert e-waste to high-value-added and high-efficient photocatalyst, which is significant for waste utilization and environmental protection.