Metal‐free graphite carbon nitride (g‐C₃N₄), has garnered significant attention for photocatalytic water‐splitting applications. However, its practical use is hindered by the rapid recombination of photogenerated electrons and holes, which limits its photocatalytic efficiency. In this study, series photocatalysts were designed by coupling g‐C₃N₄ with TiO2 derived from Ti3C2 MXene of varying thickness. The heterojunctions were synthesized through the calcination method, leveraging the unique properties of single‐layer and multilayer Ti3C2 MXene as precursors for TiO2. Comprehensive characterization revealed the successful formation of g‐C₃N₄/TiO₂ type II heterojunctions, facilitating the efficient separation of photogenerated electrons‐holes. The photocatalytic hydrogen production performance of the composites, with the optimal CN/S‐TO (8.26 mmol/h/g) and CN/M‐TO (11.6 mmol/h/g) samples demonstrated hydrogen evolution rates of 2.7 and 3.5 times higher than pristine g‐C₃N₄, respectively. This enhancement is attributed to the intimate heterojunction formed between TiO₂ and g‐C₃N₄, which effectively promotes the transfer of photogenerated charges while suppressing the recombination of electrons and holes. Additionally, multilayer‐derived TiO2 retained a more stable structure post‐calcination, offering superior electron transport channels compared to its single‐layer counterpart. These findings underscore the potential of MXene‐derived heterojunctions based on different thicknesses as efficient photocatalysts for sustainable hydrogen production.

Performing designed, abiotic chemical transformations in live environments represents a powerful approach to interrogate and manipulate biology, and to uncover new types of biomedical tools. Despite significant advances in the area, the list of bioorthogonal reactions so far available is still very short, and mainly restricted to the use of strained reactants, or metal‐promoted processes. En route to further expanding the repertoire of biocompatible reactions, we demonstrate here that aryldiazonium salts, well‐established as radical precursors, can react with unsaturated systems in biologically relevant media under photocatalytic conditions, to give either addition or cycloaddition products, depending on the reactants.

Various chemical transformation approaches are being actively developed to address the environmental accumulation of plastic waste. However, most postconsumer plastics are heterogeneous, exhibit high melt viscosity, and are insoluble in most conventional solvents. Such properties result in transport‐limiting chemical transformations, resulting in low conversion rates, and low product selectivity. Although supercritical fluids (SCFs) have been a matter of continuing scientific interest in several mass‐transfer processes, the use of SCFs as tunable media for the chemical transformation of postconsumer plastics is still in its early stages, but has rapidly advancing in recent years. Therefore, this review reports on the current state‐of‐art of chemical transformation of plastics using SCFs. It addresses the effects of sub‐and supercritical CO2 (scCO2) on solvolysis‐based technologies. Also, it reviews recent advances on the use of supercritical organic solvents (e.g., ethanol, methanol) and supercritical water (SCW) as reaction media for the solvolysis and liquefaction of plastics, respectively, and the latest developments in the simultaneous conversion of CO2 and waste plastics. Overall, developing technologies that minimize mass transfer limitations during chemical transformation of plastics is critical to overcome some of the major bottlenecks hampering product yield and selectively, and ultimately the economic viability of plastics recycling and upcycling.

Dilute atom alloys (DAAs) are an important class of heterogeneous catalysts due to their ability to precisely tune the activity and selectivity of reactions. DAA catalysts typically consist of a small quantity of metal solute in a metal host. Key considerations in the stability of DAA catalysts are the segregation and aggregation energy. In this work, we report a systematic theoretical study of segregation and aggregation energies of DAA catalysts composed of 3d, 4d, and 5d transition metals. To investigate the nature of DAAs, we analyzed both Bader charge and density of states, as well as formation energies to identify the most stable DAA configuration for a given alloy. We further applied regression‐based, tree‐based, and neural network machine learning (ML) models to gain physics‐based insights in predicting segregation and aggregation energies based on readily available atomic and bulk features. We found that the d‐band filling of the solute and host, nearest neighbor distance of the host and d‐band width of the solute determine the segregation energy while the Pauling electronegativity of the host and solute, nearest neighbor distance of the host, and cohesive energy of host determine aggregation energy. Our findings provide crucial insights for DAA catalyst design.

Metal supported catalysts play a pivotal role in various industrial processes, yet conventional preparation methods such as impregnation or coprecipitation lack precision in controlling critical parameters like particle size, morphology, and composition. The colloidal synthesis proved to be an excellent route for the rational adjustment of these parameters, allowing to establish structure‐performance correlations for smart catalyst design. This review explore the common strategies employed for the fine tuning of size, shape, and composition of colloidal nanoparticles used as heterogeneous catalysts. Since the colloidal route involves the use of stabilizing agents, different strategies for their removal are discussed together with insights into their effects in catalysis. Furthermore, common strategies for the deposition of preformed nanoparticles are presented. . In addition, the modifications in the geometric and electronic properties and their impact in the catalytic properties are described. To conclude, current applications, challenges, and future perspectives of metal supported nanoparticles as heterogenous catalysts are discussed.

Amino acid transaminases (ATs) have garnered considerable attention in recent years as promising biocatalysts for the synthesis of high‐value chiral chemicals, including both natural and non‐canonical amino acids. These enzymes catalyze the transfer of amino groups from amino acids to keto acids, playing a pivotal role in various biological processes and industrial applications. Characterized by their high turnover rates, remarkable enantioselectivity, and broad substrate specificity, ATs exhibit exceptional versatility and potential. This review presents a comprehensive overview of the classification, reaction mechanisms, and activity assays of ATs. More crucially, we delve into the recent advancements in protein engineering of ATs through directed evolution and rational/semi‐rational design strategies, which have been instrumental in addressing limitations such as low catalytic efficiency and stability. Furthermore, we survey the recent synthetic applications of ATs in the production of aliphatic and aromatic amino acids, highlighting smart amino donors and coupling methods that effectively shift the equilibrium of transamination reactions, as well as enzyme cascades that further expand the scope of reactions. By bridging gaps in research on ATs, this review aims to provide valuable insights and guide for future developments in the field of biocatalysis, ultimately fostering their continued utilization and advancement.

Designing heterogeneous catalysts that ensure efficient recycling and reuse of the catalyst in a wide range of transformations remains a real challenge. In this contribution, targeted copolymers are used as supports for the development of heterogeneous asymmetric catalysts. They are made up of two methacrylate monomers, 3‐azidopropylmethacrylate (AZMA), and 2‐methoxyethyl methacrylate (MEMA) used as a diluting agent. Polymerization was carried out using Cu(0)‐mediated reversible deactivation radical polymerization (RDRP), yielding two copolymers with controlled MEMA/AZMA compositions of 70/30 and 30/70 with moderate dispersity control (Ð = 1.32‐1.54), targeting polymers with a similar molar mass, which is important to achieve precise control of the catalyst loading to implement asymmetric catalysis. The copolymers were post‐functionalized using click chemistry with two salen complexes containing a chromium or a cobalt center, these species being recognized for their broad range of applications. The supported catalysts were evaluated in two reactions and recovered by precipitation and filtration techniques. The first reaction involved the asymmetric ring opening (ARO) of cyclohexene oxide with trimethylsilylazide, catalyzed by the chromium sites, the second reaction was the dynamic kinetic resolution (DKR) of epibromohydrin with water, promoted by the cobalt sites. The recycling was effective, demonstrating the robustness and viability of the procedure.

Heterogeneous rhenium catalysts supported on various oxides, particularly TiO2, have demonstrated effectiveness in converting carbon dioxide (CO2) to methanol via hydrogenation, showing high selectivity under diverse reaction conditions. However, the impact of different rhenium precursors on the catalytic performance and physicochemical properties of ReOx/TiO2 has not yet been elucidated. Herein, we compared catalysts prepared from NH4ReO4 and Re2O7 precursors with varying rhenium content (4 to 14 wt% Re) synthesized using a wet impregnation approach. These catalysts were evaluated under different reaction temperatures (200‐250 ºC), pressures (100‐200 bar), and H2/CO2 ratios (1‐4). This study revealed that both catalytic performance and physicochemical properties varied not only with the type of precursor but also with the rhenium content. Variation in reduction temperature, particle size, oxidation states of Re and surface Re=O terminals were observed. In batch system, catalysts derived from NH4ReO4 demonstrated a higher selectivity for methanol production under high pressure and stoichiometric conditions, regardless of temperature. In contrast, Re2O7‐based catalysts demonstrated higher methanol selectivity at 200°C, with H2/CO2 ratios between 1 and 3, regardless of the total pressure. These findings provide a deeper and valuable insight on the choice of precursors for the preparation of ReOx/TiO2 catalysts for CO2 hydrogenation.