Tuning Thermal Catalytic Enhancement in Doped MnO2-Au Nano-Heterojunctions

Author(s)

Hu, Shuhuai ^{[1, 2]} ; Liu, Xiaoyun ^[3] ; Wang, Chunrui ^{[1, 2]} ; Camargo, Pedro H. C. ^{[4, 5]} ; Wang, Jiale ^{[1, 2]}

Affiliation

^[1] Donghua Univ, Coll Sci, Shanghai 201620 - Peoples R China

^[2] Donghua Univ, Shanghai Inst Intelligent Elect & Syst, Shanghai 201620 - Peoples R China

^[3] Donghua Univ, Res Ctr Anal & Measurement, Shanghai 201620 - Peoples R China

^[4] Univ Sao Paulo, Inst Quim, Dept Quim Fundamental, Av Prof Lineu Prestes 748, BR-05508000 Sao Paulo, SP - Brazil

^[5] Univ Helsinki, Dept Chem, AI Virtasen Aukio 1, FI-00014 Helsinki - Finland

• Document type: Journal article
• Source: ACS APPLIED MATERIALS & INTERFACES; v. 11, n. 19, p. 17444-17451, MAY 15 2019.
• Web of Science Citations: 1

Abstract

Sodium (Na)- and potassium (K)-doped delta-MnO2, which presented different band gaps, were synthesized by a hydrothermal method. Then, uniform Au nanoparticles (NPs) were deposited on MnO2 to form metal-semiconductor nano-heterojunctions (MnO2-Au). By comparing their temperature-dependent thermal catalytic performances, p-aminothiophenol to p,p'-dimercaptoazobenzene conversion was used as proof-of-concept transformations. MnO2 Au hybrid materials demonstrated better thermal catalytic performances relative to individual Au NPs. Meanwhile, K-doped MnO2 Au, with a MnO2 support displaying a narrower bandgap, displayed superior catalytic activities relative to Na-doped MnO2-Au. To get the same catalytic performance by individual Au NPs, it can be similar to 50 K less by Na-doped MnO2-Au and, similar to 100 K less by K-doped MnO2-Au. The enhancement is mainly attributed to the thermally excited electrons in MnO2, which were transferred to Au NPs. The additional electrons in Au NPs increase the electron density and thus contribute to the improvement of thermal catalysis. Our findings show that the establishment of a nano-heterojunction formed by metal NPs on a semiconductor support has a significant impact on thermal catalysis, where a narrower band gap can facilitate thermally excited carriers and thus bring about better catalytic performances. Thus, the results presented here shed light on the design of a nano-heterojunction catalyst to approach reactions with superior performance under moderate conditions. (AU)

• FAPESP's process: 15/26308-7 - Optimization of the physicochemical properties of nano -structured materials for applications in molecular recognition, catalysis and energy conversion/storage
• Grantee: Roberto Manuel Torresi
• Support Opportunities: Research Projects - Thematic Grants