Synergistic Effect of the Electronic Structure and Defect Formation Enhances Photocatalytic Efficiency of Gallium Tin Oxide Nanocrystals

Abstract

The design of photocatalysts with enhanced efficiency is pivotal to sustainable environmental remediation and renewable energy technologies. Simultaneous optimization of different factors affecting the performance of a photocatalyst, including the density of active surface sites, charge carrier separation, and valence and conduction band redox potentials, remains challenging. Here, we report the synthesis of ternary gallium tin oxide (GTO) nanocrystals (NCs) with variable composition and investigate the role of Ga3+ dopants in altering the electronic structure of rutile-type SnO2 NC lattice using steady-state and time-resolved photoluminescence spectroscopies. Substitutional incorporation of Ga3+ increases the band gap of SnO2 NCs, imparting the reducing power to the conduction band electrons, and causes the formation of acceptor states, which, in conjunction with electron trapping by donors (oxygen vacancies), leads to stabilization of the photoexcited carriers. Combination of a decrease in the charge recombination rate and adjustment of the conduction band reduction potential to more negative values synergistically promote the photocatalytic efficiency of the GTO NCs. The apparent rate constant for the photocatalytic degradation of rhodamine-590 dye by optimally prepared GTO NCs is 0.39 min–1, more than 2 times greater than that by benchmark AEROXIDE TiO2 P25 photocatalyst. The results of this work highlight the concept of using rational aliovalent doping of judiciously chosen metal oxide NC lattices to simultaneously manipulate multiple photocatalytic parameters, enabling the design of versatile and highly efficient photocatalysts.

Recent Developments on Molten Salt Synthesis of Inorganic Nanomaterials: A Review

“…The molten salts help achieve phase pure products with homogeneous powder characteristics and controlled size/shape at relatively low temperature compared to the SSR . It offers advantages including being simple to operate, exhibiting rapid product formation, facilitating large scale production, being cost-effective, having low product defect density, a ligand free surface, and reproducibility, and being environment friendly. ,,,− Nanomaterials synthesized by the MSS method are generally highly homogeneous and phase pure, having controlled size and morphology, and most of the time, they have the formed particle size being in the range of tens of nanometers …”

Coumarin as a Quantitative Probe for Hydroxyl Radical Formation in Heterogeneous Photocatalysis

“…Despite the fact that heterogeneous photocatalysis was discovered almost half a century ago, numerous studies focusing on the fundamental physical chemistry of this process are still being published every year. Some of the most recent studies can be found in refs − . Presently, the primary focus is on the synthesis and characterization of photocatalysts that are tailored for specific applications, e.g., oxidative degradation of pollutants, reductive degradation of pollutants, or hydrogen production. − A general aim has been to produce photocatalysts that are activated by visible light, either to drive reactions with less energy input or to more closely match the solar spectrum.…”

“…Some of the most recent studies can be found in refs − . Presently, the primary focus is on the synthesis and characterization of photocatalysts that are tailored for specific applications, e.g., oxidative degradation of pollutants, reductive degradation of pollutants, or hydrogen production. − A general aim has been to produce photocatalysts that are activated by visible light, either to drive reactions with less energy input or to more closely match the solar spectrum. The catalytic efficiency of a photocatalyst can be increased by prolonging the lifetime of the hole–electron pair generated upon illumination.…”

“…Density functional theory calculations have become increasingly important in the design of novel photocatalysts, as well as in the characterization of existing photocatalysts. , Additionally, studies on the fundamental mechanism and reaction kinetics of photocatalytic systems are still needed. When testing the overall quantum efficiency of the photocatalytic system, chemical probes must be used. − …”

Defects and impurities in colloidal Ga2O3 nanocrystals: new opportunities for photonics and lighting

“…9 Examples include the generation of localized surface plasmon resonance in TCO nanocrystals (NCs), [15][16][17] room-temperature ferromagnetism in diluted D r a f t magnetic semiconductor oxide (DMSO) NCs, 6,[18][19][20][21][22] size-and composition-tunable light emission, [23][24][25] and selective and efficient photocatalysts. [26][27][28][29][30] Among transparent metal oxides, Ga 2 O 3 is considered the widest band gap semiconductor. Although the first systematic studies of Ga 2 O 3 were reported back in 1950's and 1960's, 7,31,32 it has been much less investigated over the ensuing decades compared to other oxides, such as ZnO, TiO 2 , or SnO 2 .…”