Plasma-assisted controllable synthesis of α-Co(OH)2 supported on multiwalled carbon nanotubes in water without precipitant addition

α-Co(OH) 2 has important applications in environmental, energy and catalysis applications. However, a complicated and harsh process is required for its production. Therefore, it is necessary to develop a rapid, facile, and green approach for the controllable synthesis of α-Co(OH) 2 . In this study, we successfully synthesized α-Co(OH) 2 supported on multiwalled carbon nanotubes (MWCNT) (α-Co(OH) 2 /MWCNT) by the plasma treatment of a mixture of cobalt nitrate and MWCNT in water without adding any other chemical reagents. The controllable synthesis of α-Co(OH) 2 was achieved only by adjusting the plasma conditions and support functionalization. The reduction of p -nitrophenol (4-NP) as a model using NaBH 4 was used to evaluate the performance of the obtained α-Co(OH) 2 /MWCNT catalysts. The results revealed that the sample prepared with 15 min of plasma treatment using H 2 /Ar as the working gas (α-Co(OH) 2 /MWCNT-15) had a good crystalline phase structure and showed excellent 4-NP reduction performance with a reaction rate constant as high as 1.97 min −1 . Structural characterization and electrochemical analyses of the different catalysts indicated that α-Co(OH) 2 /MWCNT-15 contains abundant defects, a large layer spacing, and abundant lattice sites for hydrogen adsorption, which are conducive to the adsorption of more active hydrogen species and 4-NP, and thus lead to significantly accelerated catalytic reduction of 4-NP.