Efficient Visible-Light Photocatalytic Hydrogen Evolution over the In2O3@Ni2P Heterojunction of an In-Based Metal-Organic Framework

Although the engineering of visible-light-driven photocatalysts with appropriate bandgap structures is beneficial for generating hydrogen (H₂), the construction of heterojunctions and energy band matching are extremely challenging. In this study, In₂O₃@Ni₂P (IO@NP) heterojunctions are attained by annealing MIL-68(In) and combining the resulting material with NP via a simple hydrothermal method. Visible-light photocatalysis experiments validate that the optimized IO@NP heterojunction exhibits a dramatically improved H₂ release rate of 2485.5 μmol g^-1 h^-1 of 92.4 times higher than that of IO. Optical characterization reveals that the doping of IO with an NP component promotes the rapid separation of photo-induced carriers and enables the capture of visible light. Moreover, the interfacial effects of the IO@NP heterojunction and synergistic interaction between IO and NP that arises through their close contact mean that plentiful active centers are available to reactants. Notably, eosin Y (EY) acts as a sacrificial photosensitizer and has a significant effect on the rate of H₂ generation under visible light irradiation, which is an aspect that needs further improvement. Overall, this study describes a feasible approach for synthesizing promising IO-based heterojunctions for use in practical photocatalysis.

Improved Methane Production by Photocatalytic CO2 Conversion over Ag/In2O3/TiO2 Heterojunctions

In this work, the role of In₂O₃ in a heterojunction with TiO₂ is studied as a way of increasing the photocatalytic activity for gas-phase CO₂ reduction using water as the electron donor and UV irradiation. Depending on the nature of the employed In₂O₃, different behaviors appear. Thus, with the high crystallite sizes of commercial In₂O₃, the activity is improved with respect to TiO₂, with modest improvements in the selectivity to methane. On the other hand, when In₂O₃ obtained in the laboratory, with low crystallite size, is employed, there is a further change in selectivity toward CH₄, even if the total conversion is lower than that obtained with TiO₂. The selectivity improvement in the heterojunctions is attributed to an enhancement in the charge transfer and separation with the presence of In₂O₃, more pronounced when smaller particles are used as in the case of laboratory-made In₂O₃, as confirmed by time-resolved fluorescence measurements. Ternary systems formed by these heterojunctions with silver nanoparticles reflect a drastic change in selectivity toward methane, confirming the role of silver as an electron collector that favors the charge transfer to the reaction medium.

MOFs-Derived Fusiform In2 O3 Mesoporous Nanorods Anchored with Ultrafine CdZnS Nanoparticles for Boosting Visible-Light Photocatalytic Hydrogen Evolution

The development of efficient visible-light-driven photocatalysts is one of the critically important issues for solar hydrogen production. Herein, high-efficiency visible-light-driven In₂ O₃ /CdZnS hybrid photocatalysts are explored by a facile oil-bath method, in which ultrafine CdZnS nanoparticles are anchored on NH₂ -MIL-68-derived fusiform In₂ O₃ mesoporous nanorods. It is disclosed that the as-prepared In₂ O₃ /CdZnS hybrid photocatalysts exhibit enhanced visible-light harvesting, improves charges transfer and separation as well as abundant active sites. Correspondingly, their visible-light-driven H₂ production rate is significantly enhanced for more than 185 times to that of pristine In₂ O₃ nanorods, and superior to most of In₂ O₃ -based photocatalysts ever reported, representing their promising applications in advanced photocatalysts.