RESUMO
The higher amount of Pt usage and its poisoning in methanol oxidation reaction in acidic media is a major setback for methanol fuel cells. Herein, a promising dual application high-performance electrocatalyst has been developed for hydrogen evolution and methanol oxidation. A low Pt-content nanoalloy co-doped with Cu, Mn, and P is synthesized using a modified solvothermal process. Initially, ultrasmall ≈2.9 nm PtCuMnP nanoalloy is prepared on N-doped graphene-oxide support and subsequently, it is characterized using several analytical techniques and examined through electrochemical tests. Electrochemical results show that PtCuMnP/N-rGO has a low overpotential of 6.5 mV at 10 mA cm-2 in 0.3 m H2 SO4 and high mass activity for the hydrogen evolution reaction. For the methanol oxidation reaction, the PtCuMnP/N-rGO electrocatalyst exhibits robust performance. The mass activity of PtCuMnP/N-rGO is 6.790 mA mg-1 Pt , which is 7.43 times higher than that of commercial Pt/C (20% Pt). Moreover, in the chronoamperometry test, PtCuMnP/N-rGO shows exceptionally good stability and retains 72% of the initial current density even after 20,000 cycles. Furthermore, the PtCuMnP/N-rGO electrocatalyst exhibits outstanding performance for hydrogen evolution and methanol oxidation along with excellent anti-poisoning ability. Hence, the developed bifunctional electrocatalyst can be used efficiently for hydrogen evolution and methanol oxidation.
RESUMO
Methylene blue is a dye that is extensively used in the textile industry but it is a hazardous, carcinogenic, and mutagenic pollutant. Therefore, the treatment of wastewater containing methylene blue by photocatalytic degradation under visible light without using any sacrificial agent (H2O2) is an important method towards attaining an eco-friendly environment. Herein, the nanocomposite of Ag-doped TiO2 on WO3 nanoparticles (Ag@TiO2/WO3) was prepared by a modified sol-gel precipitation route, and their physicochemical properties were studied. The bandgap of Ag sensitized metal oxide nanocomposite in Ag@TiO2/WO3 was slightly reduced compared to the pristine titania due to the creation of interstitial energy states during colligation of titania and tungsten oxide. The ease of charge carrier transfers through the heterojunction of TiO2/WO3 increased the photocatalytic activity of the photocatalyst. Furthermore, in Ag@TiO2/WO3 the plasmonic Ag sensitization to the host semiconductor TiO2 has further boosted the rate of photocatalytic degradation because of the surface plasmon resonance (SPR) and hindrance of charge carrier recombination. Due to the synergistic effect of SPR and the presence of heterojunction in Ag@TiO2/WO3, the photocatalytic activity was found to be 25 times higher for Ag@TiO2/WO3 than that of commercial DP25 photocatalyst under visible light towards methylene blue degradation.
