High-quality Pt-based catalysts are highly desirable for ethanol oxidation reaction (EOR), which is of critical importance for the commercial applications of direct ethanol fuel cells (DEFCs). However, most of the Pt-based catalysts have suffered from high cost and low operation durability. Herein a two-step method has been developed to synthesize porous Pt nanoframes decorated with Bi(OH)₃, which show excellent catalytic activity and operation durability in both alkaline and acidic media. For example, the nanoframes show a mass activity of 6.87 A·mg_Pt^-1 in alkaline media, which is 13.5-fold higher than that of commercial Pt/C. More importantly, the catalyst can be reactivated simply, which shows negligible activity loss after running for 180,000 s. Further in situ attenuated total reflection-infrared (ATR-IR) absorption spectroscopy and CO-stripping experiments indicate that surface Bi(OH)₃ species can greatly facilitate the formation of adsorbed OH species and subsequently remove carbonaceous poison, resulting in a significantly enhanced stability towards EOR. This work may favor the tailoring of desired electrocatalysts with high activity and durability for future commercial application of DEFCs.

The surface-enhanced Raman spectroscopy (SERS) is a technique for the detection of analytes on the surface with an ultrahigh sensitivity down to the atomic-scale, yet the fabrication of SERS materials such as nanoparticles or arrays of coinage metals often involve multiple complex steps with the high cost and pollution, largely limiting the application of SERS. Here, we report a complex hierarchical metallic glassy (MG) nanostructure by simply replicating the surface microstructure of butterfly wings through vapor deposition technique. The MG nanostructure displays an excellent SERS effect and moreover, a superhydrophobicity and self-cleaning behavior. The SERS effect of the MG nanostructure is attributed to the intrinsic nanoscale structural heterogeneities on the MG surface, which provides a large number of hotspots for the localized electromagnetic field enhancement affirmed by the finite-difference time-domain (FDTD) simulation. Our works show that the MG could be a new potential SERS material with low cost and good durability, well extending the functional application of this kind of material.

Controlled synthesis of transition metal dichalcogenide (TMD) monolayers with unusual crystal phases has attracted increasing attention due to their promising applications in electrocatalysis. However, the facile and large-scale preparation of TMD monolayers with high-concentration unusual crystal phase still remains a challenge. Herein, we report the synthesis of MoX₂ (X = Se or S) monolayers with high-concentration semimetallic 1Tx phase by using the 4H/face-centered cubic (fcc)-Au nanorod as template to form the 4H/fcc-Au@MoX₂ nanocomposite. The concentrations of 1Tx phase in the prepared MoSe₂ and MoS₂ monolayers are up to 86% and 81%, respectively. As a proof-of-concept application, the obtained Au@MoS₂ nanocomposite is used for the electrocatalytic hydrogen evolution reaction (HER) in acid medium, exhibiting excellent performance with a low overpotential of 178 mV at the current density of 10 mA/cm², a small Tafel slope of 43.3 mV/dec, and excellent HER stability. This work paves a way for direct synthesis of TMD monolayers with high-concentration of unusual crystal phase for the electrocatalytic application.

High-capacity Li-rich cathode materials can significantly improve the energy density of lithium-ion batteries, which is the key limitation to miniaturization of electronic devices and further improvement of electrical-vehicle mileage. However, severe voltage decay hinders the further commercialization of these materials. Insights into the relationship between the inherent structural stability and external appearance of the voltage decay in high-energy Li-rich cathode materials are critical to solve this problem. Here, we demonstrate that structural evolution can be significantly inhibited by the intentional introduction of certain adventive cations (such as Ni²⁺) or by premeditated reservation of some of the original Li⁺ ions in the Li slab in the delithiated state. The voltage decay of Li-rich cathode materials over 100 cycles decreased from 500 to 90 or 40 mV upon introducing Ni²⁺ or retaining some Li⁺ ions in the Li slab, respectively. The cations in the Li slab can serve as stabilizers to reduce the repulsion between the two neighboring oxygen layers, leading to improved thermodynamic stability. Meanwhile, the cations also suppress transition metal ion migration into the Li slab, thereby inhibiting structural evolution and mitigating voltage decay. These findings provide insights into the origin of voltage decay in Li-rich cathode materials and set new guidelines for designing these materials for high-energy-density Li-ion batteries.

Heterojunction interfaces in perovskite solar cells play an important role in enhancing their photoelectric properties and stability. Till date, the precise lattice arrangement at TiO₂/CH₃NH₃PbI₃ heterojunction interfaces has not been investigated clearly. Here, we examined a TiO₂/CH₃NH₃PbI₃ interface and found that a heavy atomic layer exists in such interfaces, which is attributed to the vacancies of methylammonium (MA) cation groups. Further, first-principles calculation results suggested that an MA cation-deficient surface structure is beneficial for a strong heterogeneous binding between TiO₂ and CH₃NH₃PbI₃ to enhance the interface stability. Our research is helpful for further understanding the detailed interface atom arrangements and provides references for interfacial modification in perovskite solar cells.