RESUMEN
Hydrothermally derived nanocubes of CeO2(10 nm) were explored as an efficient heterogeneous catalyst in the partial oxidation of aromatic alcohols to the corresponding aldehydes and aerobic oxidation ofp-nitrotoluene top-nitrobenzoic acid. The CeO2nanocatalyst was characterized by x-ray diffraction, transmission electron microscopy (TEM), energy dispersive spectroscopy, x-ray photoelectron spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis, Fourier transform infrared spectroscopy, thermal gravimetric analysis and ultraviolet-visible spectroscopy. TEM/high-resolution TEM micrographs reveal a morphology of mostly cubic nanostructures with exposed highly active {100} and {110} facets. The surface area of nanoceria was determined by BET analysis and found to be 33.8 m2g-1. To demonstrate the universality of the catalytic system, the selective oxidation of different substrates of benzylic alcohol and complete oxidation ofp-nitrotoluene was investigated under mild conditions. Absolute selectivity towards their respective aldehydes was found to be 99.50% (benzaldehyde), 90.18% (p-chlorobenzaldehyde), 99.71% (p-nitrobenzaldehyde), 98.10% (p-fluorobenzaldehyde), 94.66% (p-anisaldehyde) and 86.14% (cinnamaldehyde). Moreover, the catalytic oxidative transformation of nitrotoluene results in 100% conversion with 99.29% selectivity towards nitrobenzoic acid.
RESUMEN
To mimic the carbon cycle at a kinetically rapid pace, the sustainable conversion of omnipresent CO2 to value-added chemical feedstock and hydrocarbon fuels implies a remarkable prototype for utilizing released CO2. Porous organic polymers (POPs) have been recognized as remarkable catalytic systems for achieving large-scale applicability in energy-driven processes. POPs offer mesoporous characteristics, higher surface area, and superior optoelectronic properties that lead to their relatively advanced activity and selectivity for CO2 conversion. In comparison to the metal organic frameworks, POPs exhibit an enhanced tendency toward membrane formation, which governs their excellent stability with regard to remarkable ultrathinness and tailored pore channels. The structural ascendancy of POPs can be effectively utilized to develop cost-effective catalytic supports for energy conversion processes to leapfrog over conventional noble metal catalysts that have nonlinear techno-economic equilibrium. Herein, we precisely surveyed the functionality of POPs from scratch, classified it, and provided a critical commentary of its current methodological advancements and photo/electrochemical achievements in the CO2 reduction reaction.
RESUMEN
The advent of two-dimensional layered materials has bolstered the development of catalytic endeavors for energy conversion and storage. MXenes (transition metal carbides/nitrides) have already consolidated their candidature in the past decade due to their enhanced compositional and structural tunabilities through surface modifications. Perseverant research in engineering MXene based materials has led to the inception of MBenes (transition metal borides) as promising catalytic systems for energy-driven operations. Physicochemical superiorities of MBenes such as escalated conductivity and hydrophilicity, unique surface and geometrical domains, and higher stability and modulus of elasticity provide the reaction-friendly milieu to exploit these materials. Nevertheless, the research on MBenes is embryonic and requires the thorough realization of their scientific significance. Herein, we aim to discuss the advancements, challenges, and outlooks of MBenes with respect to their energy conversion HER, CO2RR, and NRR applications.
RESUMEN
Highly efficient nanocatalysts with a high specific surface area were successfully synthesized by a cost-effective and environmentally friendly hydrothermal method. Structural and elemental purity, size, morphology, specific surface area, and band gap of pristine and 1 to 5% Cu-doped TiO2 nanoparticles were characterized by powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), energy dispersive X-ray analysis (EDAX), inductively coupled plasma mass spectrometry (ICP-MS), liquid chromatography-high resolution mass spectrometry (LC-HRMS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET surface area, Raman spectroscopy, photoluminescence spectroscopy (PL) and UV-visible diffused reflectance spectroscopy (UV-DRS) studies. The XPS and EPR findings indicated the successful integration of Cu ions into the TiO2 lattice. UV-DRS and BET surface area investigations revealed that with an increase in dopant concentration, Cu-doped TiO2 NPs show a decrease in band gap (3.19-3.08 eV) and an increase in specific surface area (169.9-188.2 m2/g). Among all compositions, 2.5% Cu-doped TiO2 has shown significant H2 evolution with an apparent quantum yield of 17.67%. Furthermore, the electrochemical water-splitting study shows that 5% Cu-doped TiO2 NPs have superiority over pristine TiO2 for H2 evolution reaction. It was thus revealed that the band gap tuning with the desired dopant concentration led to enhanced photo/electrocatalytic sustainable energy applications.
RESUMEN
The simultaneous realization of sustainable energy and gas sensors dealing with the emission of pollutants is indispensable as the former thrives on the minimization of the latter. However, there is a dearth of multifunctional nanocatalysts in the literature. This ascertains the importance of multifunctional semiconductors which can be utilized in H2 generation via overall water splitting and in the gas sensing of global pollutants such as NH3. MoO3-decorated TiO2 Z-scheme heterostructures exceptionally escalate the photochemical and photo/electrochemical H2 evolution performance and gas sensing response of TiO2 owing to the synergistic relationship between TiO2 and MoO3. Extensive structural, morphological, and optical characterizations, theoretical studies, and XPS results were exploited to develop a mechanistic framework of photochemical H2 evolution. The photochemical response of the optimum TiO2-MoO3 composition (20 wt % MoO3-TiO2) was found to be nearly 12- and 20-fold superior to the pristine TiO2 and MoO3 photocatalysts, respectively, with the remarkable H2 evolution rate of 9.18 mmol/g/h and AQY of 36.02%. In addition, 20 wt % MoO3-TiO2 also showed advanced photo/electrochemical efficiency with 0.61/0.7 V overpotential values toward HER due to the higher electrochemically active surface area and Tafel slope as low as 65 mV/dec. The gas sensing response of 20 wt % MoO3-TiO2 toward NH3 gas turned out to be 2.5-fold higher than that of the pristine TiO2 gas sensor.