The world scenario regarding consumption and demand for products based on fossil fuels has demonstrated the imperative need to develop new technologies capable of using renewable resources. In this context, the use of biomass to obtain chemical intermediates and fuels has emerged as an important area of research in recent years, since it is a renewable source of carbon in great abundance. It has the benefit of not contributing to the additional emission of greenhouse gases since the CO₂ released during the energy conversion process is consumed by it through photosynthesis. In the presented review, the authors provide an update of the literature in the field of biomass transformation with the use of niobium-containing catalysts, emphasizing the versatility of niobium compounds for the conversion of different types of biomass.

Carbon nitrides are among the most efficient and extensively studied transition‐metal‐free photocatalysts, yet their industrial application is limited by high charge recombination, poor charge transport, and insufficient absorption above 460 nm. This study investigates how fine‐tuning the crystal structure of carbon nitrides helps to overcome these challenges and to enhance their photocatalytic performance. We used poly(heptazine imides) (PHIs) with various cations (M = H⁺, Na⁺, K⁺, Mg ² ⁺) as a model system. Na‐PHI exhibits the highest activity among PHIs with monovalent cations, as the combination of solvated Na⁺ cations and rotational defects, experimentally observed in this study for the first time, optimizes interlayer charge transfer. Greater photocatalytic efficiency observed for Mg‐PHI is attributed to the preservation of rotational defects and the higher oxidation state of Mg ² ⁺, which enhances charge density and facilitates charge transfer. Density functional theory (DFT) and spectroscopic analyses reveal that Na‐PHI and Mg‐PHI share a valence band dominated by nitrogens and a conduction band primarily influenced by carbons, with both cations contributing to n‐type doping. Mg‐PHI features sub‐gap impurity states, reducing the band gap and extending light absorption. Excited‐state molecular dynamic simulations further demonstrate that water molecules contribute more significantly to charge transfer. highlighting an additional key factor in optimizing photocatalytic performance.

Methane conversion to valuable chemicals is a highly challenging and desirable reaction. Photocatalysis is a clean pathway to drive this chemical reaction, avoiding the high temperature and pressure of the syngas process. Titanium dioxide, being the most used photocatalyst, presents challenges in controlling the oxidation process, which is believed to depend on the metal sites on its surface that function as heterojunctions. Herein, we supported different metals on TiO₂ and evaluated their activity in methane photooxidation reactions. We showed that Ni-TiO₂ is the best photocatalyst for selective methane conversion, producing impressively high amounts of methanol (1.600 μmol·g^-1) using H₂O₂ as an oxidant, with minimal CO₂ evolution. This performance is attributed to the high efficiency of nickel species to produce hydroxyl radicals and enhance H₂O₂ utilization as well as to induce carrier traps (Ti³⁺ and SETOVs sites) on TiO₂, which are crucial for C-H activation. This study sheds light on the role of catalyst structure in the proper control of CH₄ photoconversion.