The separation of photogenerated carriers and photocatalytic hydrogen production efficiency was greatly enhanced by the 2D/2D heterojunction of Ti3C2/g-C3N4.

Although hexagonal boron nitride (h‐BN) has recently been identified as a highly efficient catalyst for the oxidative dehydrogenation of propane (ODHP) reaction, the reaction mechanisms, especially regarding radical chemistry of this system, remain elusive. Now, the first direct experimental evidence of gas‐phase methyl radicals (CH3.) in the ODHP reaction over boron‐based catalysts is achieved by using online synchrotron vacuum ultraviolet photoionization mass spectroscopy (SVUV‐PIMS), which uncovers the existence of gas‐phase radical pathways. Combined with density functional theory (DFT) calculations, the results demonstrate that propene is mainly generated on the catalyst surface from the C−H activation of propane, while C2 and C1 products can be formed via both surface‐mediated and gas‐phase pathways. These observations provide new insights towards understanding the ODHP reaction mechanisms over boron‐based catalysts.

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Titanium dioxide (TiO2) represents a promising candidate for hydrogen production via photocatalysis. However, its large bandgap and fast charge recombination limits its efficiency. To overcome this limitation, we explored in this work two-dimensional titanium carbide MXene, Ti3C2 T x (T x = O, OH, F), as feasible co-catalysts for hydrogen production with TiO2 as the photocatalyst. We synthesized a series of Ti3C2 T x /TiO2 composite photocatalysts with monolayer Ti3C2 T x as the co-catalyst to improve the separation of photoinduced electrons and holes. The physicochemical properties of the Ti3C2 T x /TiO2 composites were investigated by a variety of characterization techniques, and the effect of the monolayer Ti3C2 T x on the photocatalytic performance of the Ti3C2 T x /TiO2 composites is elucidated by comparison to the multilayer counterpart. The photocatalytic hydrogen evolution rate of the optimized monolayer Ti3C2 T x /TiO2 composite is over 9 times higher than that of the pure TiO2 and 2.5 times higher than the multilayer counterpart. The significantly enhanced activity is attributed to the superior electrical conductivity of monolayer Ti3C2 T x and charge-carrier separation at the MXene/TiO2 interface. A mechanism of photocatalytic hydrogen evolution over the Ti3C2 T x /TiO2 system is proposed. This work demonstrates the potential of monolayer MXenes as effective co-catalysts for photocatalysis and further broadens the applications of the MXene family of two-dimensional materials.

The development of highly active, eco-friendly, and structurely fine-tunable organic luminophores is currently desirable for electrochemiluminescence (ECL). Tetraphenylethene (TPE) derivatives are the most representative aggregation-induced emission characteristic (AIEgens). In contrast, their aggregation-induced ECLs have not been detail studied. Herein, we report the bright cathodic aggregated state ECL of TPE derivatives by a coreactant approach. In this system, the substituents profoundly affect ECL emissions by changing the relative intensities of R and B band intensity ratios in their UV–vis spectra as well as the HOMO and LUMO energies. It was discovered that electron-withdrawing nitro-substituted TPE-(NO2)4 with a smaller LUMO/HOMO band gap and stronger R band featured the strongest ECL emissions and became the best luminophore for the highly efficient detection of iodide (I–) in the aqueous phase. This work not only reveals the influence of R and B bands in TPE derivative UV–vis spectra on their optical properties but also constructs a novel aggregation-induced ECL sensing.

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Methane conversion has received renewed interest due to the rapid growth in production of shale gas. Methane combustion for power generation and transportation is one of the alternatives for methane utilization. However, complete conversion of methane is critical to minimize negative environmental effects from unburned methane, whose noxious effect is 25 times greater than that of CO 2 . Although perovskite catalysts have high thermal stability, their low activities for methane combustion prevent them from being utilized on a commercial basis. In this work, we show the impact from reconstruction of surface and subsurface monolayers of perovskite catalysts on methane combustion, using SrTiO 3 (STO) as a model perovskite. Several STO samples obtained through different synthetic methods and subjected to different postsynthetic treatments were tested for methane combustion. Through top surface characterization, kinetic experiments (including isotope labeling experiments) and density functional theory calculations, it is shown that both surface segregation of Sr and creation of step surfaces of STO can impact the rate of methane combustion over an order of magnitude. This work highlights the role of surface reconstruction in tuning perovskite catalysts for methane activation.

Monolayer Ru atoms covered highly ordered porous Pd octahedra have been synthesized via the underpotential deposition and thermodynamic control. Shape evolution from concave nanocube to octahedron with six hollow cavities was observed. Using aberration-corrected high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy, we provide quantitative evidence to prove that only a monolayer of Ru atoms was deposited on the surface of porous Pd octahedra. The as-prepared monolayer Ru atoms covered Pd nanostructures exhibited excellent catalytic property in terms of semihydrogenation of alkynes.