MoS₂ is an important two-dimensional transition metal dichalcogenide (TMD), whose physical and chemical properties are closely related to its layer number, size, defects, and crystal structure. Therefore, the controllable synthesis of phase-pure monolayer MoS₂ represents a key challenge. Herein, we report a simple and efficient wet-chemical synthesis strategy for 1T-MoS₂ and 2H-MoS₂, with the crystal phase controlled by the reaction temperature. At 220 °C, ultra-small (1–2 nm) monolayer 1T-MoS₂ colloids are obtained; at 250 °C, monolayer 2H-MoS₂ nanosheets are produced. Both materials exhibit good dispersibility in nonpolar solvents and can be readily spin-coated into thin films. Interestingly, the 1T-MoS₂ and 2H-MoS₂ exhibit different exciton dynamics in transient absorption (TA) spectra, but similar trap state-induced negative photoconductivity (NPC) under near-infrared (825 nm) illumination. These findings provide new perspectives for the design of MoS₂-based optoelectronic devices.

Pd-based metallic nanosheets with advanced physicochemical properties have been widely prepared and employed in various electrocatalytic reactions. However, few concerns were focused on their multiple performances in different electrocatalysis. Here, highly curved and ultrathin PdNiRu nanosheets (NSs) are developed by facile wet-chemistry strategy and exhibit excellent electrocatalytic performance toward both oxygen reduction reaction (ORR) and ethylene glycol oxidation reaction (EGOR). Owing to the synergistically structural (e.g., ultrathin, curved, defects/steps-rich) and compositional (ternary alloy) advantages, PdNiRu NSs exhibited enhanced ORR and EGOR specific/mass activities and better stability/durability than control electrocatalysts. The specific activity (5.52 mA·cm⁻²) and mass activity (1.13 A·mg_Pd⁻¹) of the PdNiRu NSs in ORR are 4.8 and 3.4 times as the ones of commercial Pt/C, respectively. The mass activity of PdNiRu NSs (3.86 A·mg_Pd⁻¹) in EGOR is 2.6 times as commercial Pd/C (1.51 A·mg_Pd⁻¹). This study is helpful for the development of desired electrocatalysts with multi-functional application in practical fuel cells.

Porous features of mesoporous metal nanocrystals are critically important for their applications in catalysis, sorption, and biomedicine and bioimaging. However, precisely engineering porous architectures of mesoporous metals is still highly challenging. Herein, we report a facile soft-templating strategy to precisely engineer porous architectures of multicomponent PdCuBP mesoporous nanospheres (MSs) by using the surfactants with different amphiphilic features. Three kinds of MSs with distinct porous architectures, including three-dimensional (3D) opened/interconnected dendritic mesopores (dMSs), one-dimensional (1D) cylindered mesopores (cMSs), and zero-dimensional (0D) spherical mesopores (sMSs), are prepared. This surfactant-templating method is generally extended to regulate elemental compositions of multicomponent MSs. The resultant Pd-based MSs have been evaluated as the electrocatalysts for ethanol oxidation reaction (EOR). Our results show that quaternary PdCuBP dMSs display remarkably high catalytic activity and better stability for electrocatalytic EOR, compared to those of multicomponent MSs with other porous architectures and less elemental compositions. Mechanism studies reveal that PdCuBP dMSs combine multiple structural and compositional advantages, which kinetically accelerate the electron/mass transfers and also improve the tolerances to poisoning intermediates. We believe that the porous architecture engineering in mesoporous metal electrocatalysts will present a new way to design highly efficient electrocatalysts with desired porous systems and explore their relations towards (electro)catalysis.