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g-C3N4 emerges as a promising metal-free semiconductor photocatalyst due to its cost-effectiveness, facile synthesis, suitable visible light response, and robust thermal stability. However, its practical application in photocatalytic hydrogen evolution reaction (HER) is impeded by rapid carrier recombination and limited light absorption capacity. In this study, we successfully develop a novel g-C3N4-based step-scheme (S-scheme) heterojunction comprising two-dimensional (2D) sulfur-doped g-C3N4 nanosheets (SCN) and one-dimensional (1D) FeCo2O4 nanorods (FeCo2O4), demonstrating enhanced photocatalytic HER activity. The engineered SCN/FeCo2O4 S-scheme heterojunction features a well-defined 2D/1D heterogeneous interface facilitating directed interfacial electron transfer from FeCo2O4 to SCN, driven by the lower Fermi level of SCN compared to FeCo2O4. This establishment of electron-interacting 2D/1D S-scheme heterojunction not only facilitates the separation and migration of photogenerated carriers, but also enhances visible-light absorption and mitigates electron-hole pair recombination. Band structure analysis and density functional theory calculations corroborate that the carrier migration in the SCN/FeCo2O4 photocatalyst adheres to a typical S-scheme heterojunction mechanism, effectively retaining highly reactive photogenerated electrons. Consequently, the optimized SCN/FeCo2O4 heterojunction exhibits a substantially high hydrogen production rate of 6303.5 µmol·g−1·h−1 under visible light excitation, which is 2.4 times higher than that of the SCN. Furthermore, the conjecture of the S-scheme mechanism is confirmed by in situ XPS measurement. The 2D/1D S-scheme heterojunction established in this study provides valuable insights into the development of high-efficiency carbon-based catalysts for diverse energy conversion and storage applications. [ABSTRACT FROM AUTHOR]

HCHO is one of the volatile organic compounds (VOCs), whose toxicity and volatility have a significant effect on health and the environment. In this study, Sc/Cr2CO2 as a single-atom catalyst was investigated for the oxidation of HCHO using thermal catalysis and density functional theory (DFT). Sc/Cr2CO2 shows excellent thermal stability as revealed from ab initio molecular dynamic (AIMD) simulations. With an increase in temperature, the adsorption of O2 and HCHO on Sc/Cr2CO2 is enhanced. The results of Gibbs free energy indicate that the catalytic reactivity of Sc/Cr2CO2 is enhanced for HCHO when temperature is increased. For the dissociation of O–H bonds, the diffusion barriers of high temperature (448 K) are lower than those of room temperature (298 K) at the Eley-Rideal (ER) path, which indicates that the reaction can be promoted for the ER path at high temperatures. Thus, Sc/Cr2CO2 can be a promising high-temperature HCHO oxidation candidate. This work may pave the way for the next generation of advanced catalytic materials for high-efficiency catalytic HCHO oxidation with the kiln exhaust gas. [ABSTRACT FROM AUTHOR]

In the pursuit of sustainable energy solutions, the carbon dioxide reduction reaction (CO2RR) holds immense promise for converting CO2 into valuable chemicals and fuels. In this view, the exploration of magnetic MXene catalysts is crucial for understanding their reactivity and performance in electrochemical reactions to improve the CO2 conversion process. Herein, two distinct magnetic configurations, ferromagnetic (FM) and antiferromagnetic (AFM), were considered for La-doped Ti3C2O2 (La-Ti3C2O2). Using density functional theory (DFT) calculations, the first principles simulation was carried out to evaluate the electronic properties, magnetic properties, and CO2RR potential of these configurations. Our findings reveal an enhancement in semiconductivity and surface reactivity of the La-Ti3C2O2 catalyst, resulting in improved electron transfer characteristics. This facilitates CO2 adsorption and decreases the formation energy barrier of intermediate species towards the CO2 hydrogenations. The La-Ti3C2O2 catalyst showed a better performance than the parent molecule Ti3C2O2, which suffers from an insufficiency of reactivity on its surface. Furthermore, the study demonstrates the AFM structure of La-Ti3C2O2 to be the soundest, which thereby displays a better efficiency than the FM structure. Considering our findings, during the current CO2 conversion process, the reaction pathway with a less energy consumption must be preferred over others. [ABSTRACT FROM AUTHOR]