Time and temperature dependent formation of hollow gold nanoparticles via galvanic replacement reaction of As(0) and its catalytic application

Two different sized As(0) nanoparticles As1 (50 ± 7 nm) and As2 (70 ± 10 nm) are prepared by reducing arsenite with NaBH4 in the pH range 7-9, at controlled temperature (10 and 40 °C). Further, galvanic replacement reaction is used exploiting the reducing nature of As(0) to prepare two different sized hollow gold nanoparticles (HGNPs) AuNP1 (55 ± 7 nm) and AuNP2 (72 ± 7 nm). These HGNPs exhibit high catalytic activity towards 4-nitrophenol reduction under various conditions following first-order kinetics. AuNP1 shows ~6.6 time higher turnover frequency compared with that of AuNP2 due to its smaller size. Both catalysts are recycle able.