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Understanding the glass-like thermal conductivity (κ) in simple-composition crystalline materials is critical for the development and design of low‒ κ materials. Here, we report the origin of glass-like low κ in binary crystalline tantalates RETa 3 O 9 (RE = Nd, Sm, Eu, Gd) by atomistic simulation. It is found that the low κ is mainly due to the rattling effect of RE3+ cations arising from the large difference in the interatomic bonding between O‒RE and O‒Ta. The vibrational mode decomposition results reveal that most modes in RETa 3 O 9 fall in the Ioffe–Regel regime and exhibit a strongly diffusive nature due to the fluctuating interatomic force of O‒Ta in the TaO 6 octahedron. The dual-phonon model reveals that the vast majority (>97%) of heat in RETa 3 O 9 is transported by diffusive modes rather than propagating modes. Consequently, the thermal conduction in RETa 3 O 9 exhibits a unique glass-like nature. Contrary to conventional belief, the optical phonon modes in RETa 3 O 9 play a significant role in thermal conduction. Overall, the new insight into the link between chemical binding and glass-like κ serves to the development and design of low‒ κ materials for thermoelectric and thermal management applications. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Mg2+ doped CuCrO 2 (M:CCO) is synthesized for improving the intrinsic stability of PSCs. • A bilayer mesoscopic HTL (c-NiO x / mp -M:CCO) is constructed to address the interface contact issues. • The novel structure features well-matched energy levels, reduced reflectivity and carrier transport barrier. • The light absorption and kinetics of photo-generated carriers have been decoupled in details. • The proposed strategy enables 21.64% efficiency with excellent photo- and thermal stability. Exploitation of novel inorganic hole-transport materials (HTM) is one of the most promising approaches that achieve stable and efficient perovskite solar cells (PSCs). However, the low conductivity and large carrier transport barriers of the commonly used HTMs/perovskite system severely limit the device performance. Herein, Mg2+ doped CuCrO 2 (M:CCO) nanocrystals are synthesized using a hydrothermal method and further adopted as the HTM for inverted PSCs. The hole conductivity of CuCrO 2 is substantially enhanced upon ion doping. To address the anode/perovskite interfacial contact issues, the resultant M:CCO is designed to be a mesoporous structure atop an ultrathin compact NiO x film (5 nm). This mesoscopic structured bilayer hole-transport layers (HTLs) with well-matched graded energy levels effectively shorten the charge transport pathway, reduce carrier transport barrier in HTL/perovskite interface, and improve the light harvesting efficiency. Combined with the design of a top electron-transport layer and the usage of methylammonium (MA)-free perovskites, a champion PCE of 21.64% has been achieved, which is among the highest efficiencies for inverted MA-free, cesium/formamidinium-based PSCs to date. Moreover, the unsealed device shows excellent long-term stability: more than 91% and 80% of their initial efficiencies were retained after light soaking under 1 sun illumination for 400 h and thermal aging at 85 °C for 1000 h, respectively. This study provides a potential strategy for developing highly efficient and stable inverted PSCs. [ABSTRACT FROM AUTHOR]

A novel non-noble perovskite-type Ce 1/3 NbO 3 electrocatalyst is proposed as a promising nitrogen rediction reaction by both theoretically prediction and experimentally confirmation. • A Ce 1/3 NbO 3 perovskite is proposed and exhibits a potential N 2 activation ability by the theoretical prediction. • Experimentally, the produced ammonia from the nitrogen reduction reaction (NRR) under such Ce 1/3 NbO 3 electrocatalyst is identified successfully by the electrochemical tests, confirming our theoretical prediction. • The detailed reaction mechanism calculations conclude that NRR proceed by the distal mechanism and the potential determining step is the hydrogenation of *NH 2. Herein, a novel Ce 1/3 NbO 3 perovskite is proposed as an efficient electrocatalyst to catalyze the nitrogen reduction reaction (NRR) at ambient conditions. Density functional theory calculations are firstly used to predict the potential N 2 activation ability of Ce 1/3 NbO 3 , and then, the Ce 1/3 NbO 3 with a flower-like porous structure is prepared by a hydrothermal process and post calcination. Electrochemical tests reveal that such catalyst achieves a high NRR performance with the Faradaic efficiency of 6.87% and NH 3 yield of 10.34 µg h−1 cm−2 at −0.8 V vs RHE in 0.1 M Na 2 SO 4 , keeping up with many electrocatalysts reported recently. The mechanistic studies disclose that Nb atom is favorable as the efficient active site for NRR by the distal pathway, and Ce atom synergistically enhances the charge transfer during the NRR process. Our work provides an important reference to the rational design of the promising electrocatalysts for NRR. [ABSTRACT FROM AUTHOR]