Several different evaluation methods (EM) to obtain the band gap energy (E_g) of semiconductors via UV/Vis diffuse reflectance spectroscopy (DRS) are used in literature and no clear consensus which EM to use is established. By using P25 as a model semiconductor, evaluating 32 literature sources and our own experiments, we show that the determined E_g energy is heavily influenced by the EM (differences in E_g of up to 0.87 eV). For P25 loaded with CuO even contradictive effects of metal loading on the E_g are observed using different EM. Different phase compositions of TiO₂ are also shown to yield EM‐dependent results. This paper thus comprehensively investigates the most common EM on different relevant photocatalyst material classes, illustrates their mathematical and graphical determination, gives recommendations which method to use based on a quantitative indicator and illustrates common pitfalls in determining E_g via UV/Vis DRS.

While photocatalysis is considered a promising sustainable technology in the field of heterogeneous catalysis as well as biocatalysis, figures of merit (FOM) for comparing catalytic performance, especially between disciplines, are not well established. Here, photocatalytic water splitting was conducted using a semiconductor (NiO/La-NaTaO₃) and a bio-photocatalyst (Synechocystis sp. PCC 6803) in the same setup under similar reaction conditions, eliminating the often ill-defined influence of the setup on the FOMs obtained. Comparing the results enables the critical evaluation of existing FOMs and a quantitative comparison of both photocatalytic systems. A single FOM is insufficient to compare the photocatalysts, instead a combination of multiple FOMs (reaction rate, photocatalytic space time yield and a redefined apparent quantum yield) is superior for assessing a variety of photocatalytic systems.

Novel bifunctional metal-loaded polymer–silica composite (PSC) catalysts were investigated in the hydrodeoxygenation (HDO) of 4-(2-furyl)-3-buten-2-one (FAc) as a model substance for furfural–acetone aldol condensation products. PSC catalysts were synthesized via a sol–gel method with different polymer contents and subsequently doped with different noble metals. The product composition of the HDO of FAc could be tuned by using catalysts with different polymer (i.e., acidic properties) and metal content (i.e., redox properties), showing the great potential of metal-loaded PSC materials as tunable catalysts in biomass conversions with complex reaction networks. Furthermore, high yields (>90%) of the fully hydrodeoxygenated product (n-octane) could be obtained using noble metal-loaded PSC catalysts in only 8 h of reaction time.

One approach to increase the catalytic efficiency of TS-1 is the synthesis of TS-1 composite materials together with spherical activated carbon (SAC). Although increased Ti-site normalized catalytic activity of such composites compared to parent materials was observed, the reason for the increased activity is not fully understood. This study therefore aims to correlate the physico-chemical and catalytic activity of TS-1/SAC composites. Composite materials with different TS-1 weight fractions were prepared and applied in the heterogeneously catalyzed epoxidation of methyl oleate using aqueous H₂O₂. Up to seven times greater Ti-site normalized activity for the composites was observed compared to the parent TS-1. The pulsed field gradient (PFG) NMR was then used to rationalize the catalytic activity results. SAC was found to function similarly to a conventional catalyst support (e.g., in supported metal catalysts) for the TS-1. The SAC thus allows control of the dispersion of and pore space arrangement between TS-1 crystals, which could be directly linked to an increase in catalytic activity. In addition to gaining insight into the fundamental principles of such composite catalysts, the importance of the sorption of reactant and product molecules on the catalytic activity was pointed out.

Infrared (IR) microimaging is employed for selectively recording two‐dimensional plots of the individual distributions of the components n‐hexane (nC6) and 3‐methylpentane (3MP) over a single crystal of zeolite ZSM‐5 during mixture adsorption. At a pressure change from 0 to 0.02 mbar, the scenario of “overshooting” is observed, with the concentration of nC6 temporarily exceeding its equilibrium value. After the next pressure step from 0.02 to 2 mbar, 3MP is progressively driven out of the pores, in parallel with an increase in nC6 concentration. The IR microimaging results are corroborated by grand canonical Monte Carlo simulations, which help explain the peculiarities of mass transfer by providing visual representations of the distribution and packing densities of the guest molecules in the pores.