Highly dispersed Pd/PdO/Fe2O3 nanoparticles in SBA-15 for Fenton-like processes: confinement and synergistic effects

• Uniform and highly dispersed Pd/PdO/Fe2O3 nanoparticles in SBA-15 were fabricated.
• This catalyst has high catalytic activities in Fenton reaction for dye degradation.
• Pd and PdO play important roles in Fenton reaction.
• Synergistic effects between Fe and Pd in Fenton reaction were investigated.
• Possible mechanism for high activity of this catalyst was elucidated.

Heterogeneous Pd catalytic Fenton-like systems with in-situ-generated H2O2 have recently gained significant attention for wastewater treatment. Intense research efforts have been focused on developing highly efficient Fenton-like catalysts. It is known that nanoparticle size and appropriate coordination of active compositions are important for the fabrication of a highly efficient multicomponent catalyst. Unfortunately, effects of these factors on Fenton-like reaction are still unknown. To decipher the puzzle, we designed multicomponent Pd/PdO/Fe2O3 nanoparticles in SBA-15 (denoted as FePd-SBA) as a Fenton-like catalyst which possesses uniform and highly dispersed nanoparticles (small size about 5 nm) in space-confined channels of SBA-15. The fabricated catalyst shows high catalytic activities in Fenton-like reaction for dye degradation. For example, 98.6% removal of dye Acid Red 73 was obtained under in-situ generation of hydrogen peroxide. In contrast, when the catalyst loaded on SiO2 without channels or pores (FePd–SiO2) was prepared, and compared with FePd–SBA, FePd–SiO2 showed noticeably poor performance (51.6%) under same conditions. Obviously, such a difference in results is due to the confinement effect of SBA-15 porous channels. It was also found that Fe and Pd played important roles in the synergistic effect, that is, Pd worked in in-situ H2O2 generation and Fe species worked in decompose H2O2 to degrade organic pollutants. When we applied this catalyst for Fenton-like reaction with addition of H2O2, it was also found that Pd and PdO played important roles and the synergistic effect between Fe and Pd species actually existed in dye removal. The unique nanostructure makes the catalyst to be a novel and welcoming choice for H2O2 favorite reactions.

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