PdAuIr/C-Sb2O5·SnO2electrocatalysts with Pd∶Au∶Ir molar ratios of 90∶5∶5,70∶20∶10 and 50∶45∶5 were prepared by borohydride reduction method.These electrocatalysts were characterized by EDX,X-ray diffracti...PdAuIr/C-Sb2O5·SnO2electrocatalysts with Pd∶Au∶Ir molar ratios of 90∶5∶5,70∶20∶10 and 50∶45∶5 were prepared by borohydride reduction method.These electrocatalysts were characterized by EDX,X-ray diffraction,transmission electron microscopy and the catalytic activity toward formic acid electro-oxidation in acid medium investigated by cyclic voltammetry(CV),chroamperometry(CA)and tests on direct formic acid fuel cell(DFAFC)at 100℃.X-ray diffractograms of PdAuIr/C-Sb2O5·SnO2electrocatalysts showed the presence of Pd fcc phase,Pd-Au fcc alloys,carbon and ATO phases,while Ir phases were not observed.TEM micrographs and histograms indicated that the nanoparticles were not well dispersed on the support and some agglomerates.The cyclic voltammetry and chroamperometry studies showed that PdAuIr/C-Sb2O5·SnO2(50∶45∶5)had superior performance toward formic acid electro-oxidation at 25℃compared to PdAuIr/C-Sb2O5·SnO2(70∶20∶10),PdAuIr/C-Sb2O5·SnO2(90∶5∶5)and Pd/C-Sb2O5·SnO2electrocatalysts.The experiments in a single DFAFC also showed that all PdAuIr/C-Sb2O5·SnO2electrocatalysts exhibited higher performance for formic acid oxidation in comparison with Pd/C-Sb2O5·SnO2electrocatalysts,however PdAuIr/C-Sb2O5·SnO2(90∶5∶5)had superior performance.These results indicated that the addition of Au and Ir to Pd favor the electro-oxidation of formic acid,which could be attributed to the bifunctional mechanism(the presence of ATO,Au and Ir oxides species)associated to the electronic effect(Pd-Au fcc alloys).展开更多
The technological process of preparation of colloid Sb 2O 5 by oxidation of Sb 2O 3 with hydrogen peroxide using borax as a stabilizer has been investigated. The optimum preparation conditions selected by orthogonal f...The technological process of preparation of colloid Sb 2O 5 by oxidation of Sb 2O 3 with hydrogen peroxide using borax as a stabilizer has been investigated. The optimum preparation conditions selected by orthogonal factorization method as follows m (H 2 O)∶ m (Sb 2 O 3 )=7 5∶1, n (H 2 O 2 )∶ n (Sb 2 O 3 )=3∶1, m (Na 2 B 4 O 7 ·10H 2 O)∶ m (Sb 2 O 3 )=1∶10, 95 ℃, 1 5 h. The conversion of Sb 2 O 3 >95%, light transmittance of colloid >85% and the average diameter of Sb 2 O 5 particles was 50 nm. The colloid Sb 2 O 5 prepared was storage stable without coagulation for more than one year.展开更多
Methodology for the electrochemical decomposition of imazethapyr using Ti/SnO2-Sb2O5/PbO2 anode in Na2SO4 medium is suggested in this paper. The electrolysis reaction conditions were optimized. The process of electroc...Methodology for the electrochemical decomposition of imazethapyr using Ti/SnO2-Sb2O5/PbO2 anode in Na2SO4 medium is suggested in this paper. The electrolysis reaction conditions were optimized. The process of electrochemical decomposition was monitored by ultra-violet spectrophotometry and CODCr method. The electrochemical decomposition mechanism of imazethapyr was studied primarily by UV-VIS spectrophotometry. The effectiveness of the electrochemical pretreatment was proved by the comparative aerobic biological treatment test based on the activated sludge process.展开更多
基金the Laboratório de Microscopia do Centro de Ciências e Tecnologia de Materiais(CCTM) by TEM measurements,FAPESP(2011/18246-0,2012/03516-5) and CNPQ(150639/2013-9)for the financial support
文摘PdAuIr/C-Sb2O5·SnO2electrocatalysts with Pd∶Au∶Ir molar ratios of 90∶5∶5,70∶20∶10 and 50∶45∶5 were prepared by borohydride reduction method.These electrocatalysts were characterized by EDX,X-ray diffraction,transmission electron microscopy and the catalytic activity toward formic acid electro-oxidation in acid medium investigated by cyclic voltammetry(CV),chroamperometry(CA)and tests on direct formic acid fuel cell(DFAFC)at 100℃.X-ray diffractograms of PdAuIr/C-Sb2O5·SnO2electrocatalysts showed the presence of Pd fcc phase,Pd-Au fcc alloys,carbon and ATO phases,while Ir phases were not observed.TEM micrographs and histograms indicated that the nanoparticles were not well dispersed on the support and some agglomerates.The cyclic voltammetry and chroamperometry studies showed that PdAuIr/C-Sb2O5·SnO2(50∶45∶5)had superior performance toward formic acid electro-oxidation at 25℃compared to PdAuIr/C-Sb2O5·SnO2(70∶20∶10),PdAuIr/C-Sb2O5·SnO2(90∶5∶5)and Pd/C-Sb2O5·SnO2electrocatalysts.The experiments in a single DFAFC also showed that all PdAuIr/C-Sb2O5·SnO2electrocatalysts exhibited higher performance for formic acid oxidation in comparison with Pd/C-Sb2O5·SnO2electrocatalysts,however PdAuIr/C-Sb2O5·SnO2(90∶5∶5)had superior performance.These results indicated that the addition of Au and Ir to Pd favor the electro-oxidation of formic acid,which could be attributed to the bifunctional mechanism(the presence of ATO,Au and Ir oxides species)associated to the electronic effect(Pd-Au fcc alloys).
文摘The technological process of preparation of colloid Sb 2O 5 by oxidation of Sb 2O 3 with hydrogen peroxide using borax as a stabilizer has been investigated. The optimum preparation conditions selected by orthogonal factorization method as follows m (H 2 O)∶ m (Sb 2 O 3 )=7 5∶1, n (H 2 O 2 )∶ n (Sb 2 O 3 )=3∶1, m (Na 2 B 4 O 7 ·10H 2 O)∶ m (Sb 2 O 3 )=1∶10, 95 ℃, 1 5 h. The conversion of Sb 2 O 3 >95%, light transmittance of colloid >85% and the average diameter of Sb 2 O 5 particles was 50 nm. The colloid Sb 2 O 5 prepared was storage stable without coagulation for more than one year.
文摘Methodology for the electrochemical decomposition of imazethapyr using Ti/SnO2-Sb2O5/PbO2 anode in Na2SO4 medium is suggested in this paper. The electrolysis reaction conditions were optimized. The process of electrochemical decomposition was monitored by ultra-violet spectrophotometry and CODCr method. The electrochemical decomposition mechanism of imazethapyr was studied primarily by UV-VIS spectrophotometry. The effectiveness of the electrochemical pretreatment was proved by the comparative aerobic biological treatment test based on the activated sludge process.
