When nano-fillers are used to enhance the thermal conductivity of organic phase change materials (PCMs), the naturally formed interface is considered to hinder thermal transport of the composite PCMs. However, the effect of the interface on the thermal properties of surrounding PCM has not been fully studied. In this paper, three composite PCMs (Ery@SiC, Ery@SiO₂ and Ery@Si₃N₄) were prepared by melt-blending method. The local thermal conductivity and reduced Young’s modulus (E*) of the erythritol at the interface and far away from the interface in the composite PCMs were simultaneously measured by scanning thermal microscopy (SThM). The results revealed significant enhancement in local thermal conductivity of erythritol at the interface and its obvious positive correlation with E*. For different composite PCMs, molecular dynamics (MD) simulations suggested that the increase in intrinsic thermal conductivity and E* of erythritol is attributed to the increase in interaction energy between erythritol and nanoparticles, as more erythritol phonon vibrations transform from localized mode to delocalized mode and erythritol has a higher density at the interface. These findings will provide new ideas for the design of PCM for energy storage.

Single-atom catalysts (SACs) with high catalytic activity as well as great stability are demonstrating great promotion in electrocatalytic energy conversion, which is also a big challenge to achieve. Herein, we proposed a facile synthetic strategy to construct nickel-iron bimetallic hydroxide nanoribbon stabilized single-atom iridium catalysts (Ir-NiFe-OH), where the nickel-iron hydroxide nanoribbon not only can serve as good electronic conductor, but also can well stabilize and fully expose single-atom sites. Adopted as catalyst for urea oxidation reaction (UOR), it exhibited excellent UOR performance that it only needed a low operated potential of 1.38 V to achieve the current density of 100 mA·cm⁻². In-situ Fourier transform infrared spectroscopy, X-ray absorption spectrum, and density functional theory calculations proved that Ir species are active centers and the existence of both Ni and Fe in the local structure of Ir atom can optimize the d-band center of Ir species, promoting the adsorption of intermediates and desorption of products for UOR. The hydrogen evolution reaction (HER)/UOR electrocatalytic cell demanded voltages of 1.46 and 1.50 V to achieve 50 and 100 mA·cm⁻², respectively, which demonstrated a higher activity and better stability than those of conventional catalysts. This work opens a new avenue to develop catalysts for UORs with boosted activity and stability.

Fabricating single-atom catalysts (SACs) with high catalytic activity as well as great stability is a big challenge. Herein, we propose a precise synthesis strategy to stabilize single atomic ruthenium through regulating vanadium defects of nickel vanadium layered double hydroxides (NiV-LDH) ultrathin nanoribbons support. Correspondingly, the isolated atomically Ru doped NiV-LDH ultrathin nanoribbons (NiVRu-R) were successfully fabricated with a super-high Ru load of 12.8 wt.%. X-ray absorption spectrum (XAS) characterization further confirmed atomic dispersion of Ru. As catalysts for electrocatalytic hydrogen evolution reaction (HER) in alkaline media, the NiVRu-R demonstrated superior catalytic properties to the commercial Pt/C. Moreover, it maintained exceptional stability even after 5,000 cyclic voltammetry cycles. In-situ XAS and density functional theory (DFT) calculations prove that the Ru atomic sites are stabilized on supports through forming the Ru–O–V structure, which also help promote the catalytic properties through reducing the energy barrier on atomic Ru catalytic sites.