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A new member is incorporated into the SERS active materials family daily as a consequence of advances in materials science. Furthermore, it has been demonstrated that MXenes, which display remarkable physicochemical characteristics, are also encompassed within this family. This Review offers a comprehensive and systematic assessment of the potential of MXene structures in the context of SERS applications. First, the historical development of SERS-active substrates and the evolution of various substrates over time are analyzed. Subsequently, the formation and structural properties of MXene structures were subjected to a comprehensive and detailed examination. The principal objective of this Review is to elucidate the rationale behind the preference for MXene as a SERS-active substrate, given its distinctive physicochemical properties. In this context, while MXene's abundant surface functional groups represent a significant advantage, its high electrical conductivity, suitable flexibility, extensive two-dimensional surface areas, and antibacterial activity also warrant consideration in terms of potential applications. It is emphasized that, for MXene nanolayers to demonstrate optimal performance in SERS applications, a plan should be devised to consider these features. By increasing readers' awareness of using MXene as a SERS active substrate, potential opportunities for future application areas may be created.

Corrosion protection technology plays a crucial role in preserving infrastructure, ensuring safety and reliability, and promoting long-term sustainability. In this study, we combined experiments and various analyses to investigate the mechanism of corrosion occurring on the epoxy-based anticorrosive coating containing the additive of two-dimensional (2D) and water-stable zirconium-based metal - organic frameworks (Zr-MOFs). By using benzoic acid as the modulator for the growth of the MOF, a 2D MOF constructed from hexazirconium clusters and BTB linkers (BTB = 1,3,5-tri(4-carboxyphenyl)benzene) with coordinated benzoate (BA-ZrBTB) can be synthesized. By coating the BA-ZrBTB/epoxy composite film (BA-ZrBTB/EP) on the surface of cold-rolled steel (CRS), we found the lowest coating roughness (RMS) of BA-ZrBTB/EP is 2.83 nm with the highest water contact angle as 99.8°, which represents the hydrophobic coating surface. Notably, the corrosion rate of the BA-ZrBTB/EP coating is 2.28 × 10 -3 mpy, which is 4 orders of magnitude lower than that of the CRS substrate. Moreover, the energy barrier for oxygen diffusion through BA-ZrBTB/EP coating is larger than that for epoxy coating (EP), indicating improved oxygen resistance for adding 2D Zr-MOFs as the additive. These results underscore the high efficiency and potential of BA-ZrBTB as a highly promising agent for corrosion prevention in various commercial applications. Furthermore, this study represents the first instance of applying 2D Zr-MOF materials in anticorrosion applications, opening up new possibilities for advanced corrosion-resistant coatings.

Layered lead halide perovskites have attracted much attention as promising materials for a new generation of optoelectronic devices. To make progress in applications, a full understanding of the basic properties is essential. Here, we study 2D-layered (BA) 2 PbX 4 by using different halide anions (X = I, Br, and Cl) along with quantum confinement. The obtained cell parameter evolution, supported by experimental measurements and theoretical calculations, indicates strong lattice distortions of the metal halide octahedra, breaking the local inversion symmetry in (BA) 2 PbCl 4 , which strongly correlates with a pronounced Rashba spin-splitting effect. Optical measurements reveal strong photoluminescence quenching and a drastic reduction in the PL quantum yield in this larger band gap compound. We suggest that these optical results are closely related to the appearance of the Rashba effect due to the existence of a local electric dipole. The results obtained in ab initio calculations showed that the (BA) 2 PbCl 4 possesses electrical polarization of 0.13 μC/cm 2 and spin-splitting energy of about 40 meV. Our work establishes that local octahedra distortions induce Rashba spin splitting, which explains why obtaining UV-emitting materials with high PLQY is a big challenge.

Single-atom catalyst technology with near-100% atomic utilization and a well-defined coordination structure has provided new ideas for designing high-performance photocatalysts, which is also beneficial for reducing the usage of noble metal cocatalysts. Herein, a series of single-atomic MoS 2 -based cocatalysts where monoatomic Ru, Co, or Ni modify MoS 2 (SA-MoS 2 ) for enhancing the photocatalytic hydrogen production performance of g-C 3 N 4 nanosheets (NSs) are rationally designed and synthesized. The 2D SA-MoS 2 /g-C 3 N 4 photocatalysts with Ru, Co, or Ni single atoms show similar enhanced photocatalytic activity, and the optimized Ru 1 -MoS 2 /g-C 3 N 4 photocatalyst has the highest hydrogen production rate of 11115 μmol/h/g, which is about 37 and 5 times higher than that of pure g-C 3 N 4 and MoS 2 /g-C 3 N 4 photocatalysts, respectively. Experimental and density functional theory calculation results reveal that the enhanced photocatalytic performance is mainly attributed to the synergistic effect and intimate interface between SA-MoS 2 with well-defined coordination single-atomic structures and g-C 3 N 4 NSs, which is conducive to the rapid interfacial charge transport, and the unique single-atomic structure of SA-MoS 2 with modified electronic structure and appropriate hydrogen adsorption performance offers abundant reactive sites for enhancing the photocatalytic hydrogen production performance. This work provides new insight into improving the cocatalytic hydrogen production performance of MoS 2 by a single-atomic strategy.

Selective oxidation of alkyl-substituted phenols offers efficient access to p -benzoquinones (BQs) that serve as key components for synthesizing biologically active compounds, but rational manufacture of efficient recyclable catalysts for such a reaction remains a severe challenge. Herein, two crystalline 2D polyoxometalate-based coordination polymers (POMCPs), formulated as H 3 [Cu I 3 (L) 3 ] 2 [PM 12 O 40 ]· x H 2 O (M = Mo, x = 4 for 1 ; M = W, x = 6 for 2 ; and HL = 4-(1 H -tetazol-5-yl)pyridine), are prepared by a mineralizer-assisted one-step synthesis strategy and explored as heterogeneous catalysts for p -BQs synthesis. Both compounds have been characterized through elemental analysis, EDS analysis, infrared spectroscopy, UV-vis diffuse reflectance spectrum, EPR, XPS, BET, single-crystal, and powder X-ray diffraction. Single-crystal X-ray diffraction analysis indicates that both 1 and 2 exhibit an interesting 2D sheet structure composed of 2-connected Keggin type anions [PM 12 O 40 ] 3- and hexa-nuclear {Cu I 6 (HL) 6 } cluster-based metal-organic chains via Cu···O interactions. When used as catalysts, POMCPs 1 and 2 have excellent catalytic activities in the selective oxidation of substituted phenols to p -BQs with H 2 O 2 . Notedly, in the model reaction from 2,3,6-trimethylphenol (TMP) to the vitamin E key intermediate trimethyl- p -benzoquinone (TMBQ), the catalytic activities expressed by turnover frequency (TOF) of 1 and 2 can reach an unprecedented 2400 and 2000 h -1 , respectively, at close to 100% TMBQ yield. The truly heterogeneous nature, stability, and structural integrity of both catalysts were ascertained by FTIR, PXRD techniques, and the following cycles. Mechanism studies reveal that both catalysts can involve a dual reaction pathway through a heterolytic oxygen atom transfer mechanism and homolytic radical mechanism. Moreover, the 2D POMCPs with highly accessible bilateral active sites and efficient mass transfer efficiency possess superior catalytic performance to their analogous 3D species.

Visible-light-driven environmental contaminants control using 2D photocatalytic nanomaterials with an unconfined reaction-diffusion path is advantageous for public health. Here, cost-effective siliceous composite microsheets (FeSiO-MS) combined with two distinct refined α-Fe 2 O 3 nanospecies as photofunctional catalysts were constructed via a one-pot synthesis approach. Through precise control of Fe 2+ precursor addition, specially configured α-Fe 2 O 3 nanofibers combined with FeOx cluster-functionalized siliceous microsheets of ∼15 nm gradually evolved from the iron oxide-bearing molecular sieve, endowing a superior light-response characteristic of the formed nanocomposite. The catalytic experiment along with the ESR study demonstrated that the produced FeSiO-MS showed reinforced photo-Fenton reactivity, which was effective for rapid phenol degradation under visible light radiation. Moreover, the phenol removal process was found to be regulated by the specially configured types and concentrations of iron oxides. Notably, the obtained composites exhibited a considerable visible-light-induced bactericidal effect against E. coli . The constructed FeSiO-MS nanocomposites as integrated and eco-friendly photocatalysts exhibit enormous potentials for environmental and hygienic application.

The catalytic hydrogenation of organic compounds containing carbonyl groups has been extensively studied and widely used in industrial processes. Herein, we report the preparation of a novel nanomaterial, α-zirconium phosphate (α-ZrP) nanoplatelet-supported ruthenium nano-anadem catalyst, which possesses high selectivity in the catalytic hydrogenation of aromatic ketones. The α-ZrP nanoplatelets were prepared using a modified reflux method. Through an ion-exchange and reduction reaction pathway, ruthenium nanoparticles were loaded on ZrP to produce Ru-ZrP with a nano-anadem structure. The successful synthesis of Ru-ZrP composites is supported by a series of characterization techniques (PXRD, SEM, TEM, EDS, XPS, FT-IR, etc.). Compared with pure ZrP nanoplatelets, the catalytic hydrogenation of acetophenone has been dramatically improved when using Ru-ZrP. Full conversion was achieved at room temperature, and the yield of 1-cyclohexylehtanol was up to 95%. The effects of reaction time, reaction temperature, and hydrogen pressure were investigated. The investigation illustrates that there are two proposed reaction pathways in the hydrogenation of acetophenone, which are further supported by computational analyses. Recycling experiments indicate that the Ru-ZrP material could be reused four times without a noticeable activity decrease.

Two-dimensional (2D) perovskite solar cell (PSC) can achieve high stability by alternating interface cations. However, its main transmissive charge is limited owing to the 2D structure. Therefore, compared with a 3D device, the 2D PSC has poor power conversion efficiency (PCE). Further enhanced performance will require an increase in the transmission dimension of 2D PSC. Here, a novel tetraethylenepent (TEPA)-MAPbI 3- x Cl x analogous 2D unsymmetrical perovskite film was developed to improve the stability and PCE of the corresponding device. Based on the interaction of the active amino linear short chain of TEPA and the halogen ion, the symmetry of the mechanical structure of ions is disrupted, and the TEPA ion is embedded in the perovskite structure to form a perovskite structure with a dimension between 3D and 2D. Noticeably, the TEPA-MAPbI 3- x Cl x devices deliver high PCEs up to 19.73% which stands as the highest for MAPbI 3- x Cl x -based PSC. The environmental, thermal, and illumination stability also showed improvements ranging between 10%-30%. The enhanced PSCs are due to the higher quality of perovskite films, stronger charge transmission, and less trap density. This approach provides a new method to improve and modify 2D PSCs.

This study represents a comprehensive review about the structural features of graphene oxide (GO) and its significance in environmental applications. Two dimensional (2D) GO is tremendously focused in advanced carbon-based nanomaterials for environmental applications due to its tunable physicochemical characteristics. Herein, we report foundational structural models of GO and explore the chemical bonding of oxygen moieties, with graphite basal plane using various characterization tools. Moreover, the impact of these oxygen moieties and the morphology of GO for environmental applications such as removal of metal ions and catalytic, antibacterial, and gas sensing abilities have here been critically reviewed for the first time. Environmental applications of GO are highly significant because, in the recent era, the fast progress of industries, even in the countryside, results in air and water pollution. GO has been widely investigated by researchers to eradicate such environmental issues and for potential industrial and clinical applications due to its 2D structural features, large surface area, presence of oxygen moieties, nonconductive nature, intense mechanical strength, excellent water dispersibility, and tunable optoelectronic properties. Thence, particular emphasis is directed toward the modification of GO by varying the number of its oxygen functional groups and by coupling it with other exotic nanomaterials to induce unique properties in GO for potential environmental remediation purposes.