Deposition of Pd on Co(OH)2 nanoplates in stabilizer-free aqueous phase for catalytic reduction of 4-nitrophenol

Palladium-supported cobalt hydroxide (Co(OH)2-Pd) nanoplates were fabricated in an aqueous solution and employed as a catalyst for the reduction of 4-nitrophenol. For the preparation of Co(OH)2-Pd, Pd nanoparticles were anchored on the Co(OH)2 nanoplates after the reduction of Na2PdCl4 by ascorbic acid in the absence of a stabilizer at room temperature. The observations under transmission and scanning electron microscopy reveal that Pd nanoparticles with a size of 2–5 nm are uniformly dispersed on the surface of the Co(OH)2 nanoplates. In catalytic test, the conversion of 4-nitrophenol to 4-aminophenol is completed within 6 min in the presence of Co(OH)2-Pd(1000) nanoplates with 2.18 at.% Pd, and the corresponding kinetic constant is 0.0089 s-1 in the first test. The catalyst retains relatively high activity after several cycles. The results demonstrate that the Co(OH)2-Pd(1000) nanoplates exhibit high catalytic activity toward the reduction of 4-nitrophenol in the presence of NaBH4.