Preparation and photocatalytic performance of Bi nanoparticles by microwave-assisted method using ascorbic acid as reducing agent

•Bi NPs were prepared by MW assisted method using ascorbic acid as reducing agent.•MW-Bi NPs were very uniform and the average size was about 70 nm.•MW-Bi possessed good visible light absorption ability and the band gap was 1.77 eV.•The photocatalytic efficiency of MW-Bi was 2.7 times that of SV-Bi.•The enhanced photocatalytic activity of MW-Bi was ascribed to its small size effect.

Bismuth nanoparticles (NPs) were prepared by using microwave (MW) as heating source and ascorbic acid as reducing agent. Pure phase of Bi NPs was obtained and the size was uniform with the mean value of 70 nm. The visible light absorption was good and the optical band gap was 1.77 eV. The photocatalytic efficiency was 2.7 times that of the sample by solvothermal method for degradation of methyl blue (MB) under visible light irradiation. The hydroxyl radicals during photocatalysis were detected due to the transition of Bi from semimetal to semiconductor. The small size effect was considered to contribute a lot to the efficient photocatalytic activity.

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