Phase change material (PCM) can store heat at a constant temperature, which is beneficial to reduce building energy consumption. Herein, we fabricated a PCM board that can store 98-102 J/g heat at 26 °C. The PCM boards were paved as the floor in the real-scale office to reduce power for temperature regulation, which led to the reduced energy consumption of 18.8% and 19.7% in winter and summer, respectively. A numerical model is validated by experimental data to evaluate longterm performance. The experiment and simulation results both demonstrate the high-performance PCM floor for effective reduction in electricity consumption of heating and cooling.

For hydrogen evolution reaction (HER) in alkaline solution, the state-of-the-art platinum(Pt)-based electrocatalysts showed a bunch of drawbacks including high cost, poor durability and scarcity, making it essential to develop Pt-free electrocatalysts. In this work, we employed a double-solvent approach to prepare a ruthenium(Ru)-dispersed metal-organic framework composite, which was further pyrolyzed to obtain a novel Ru/C electrocatalyst with a Ru loading of 2.7 wt %. The target electrocatalyst showed ultrahigh activity for HER in 1 M KOH that outperformed commercial Pt/C catalyst (20 wt %) with an overpotential of 27 mV @ 25 mA cm À 2 and 86 mV @ 100 mA cm À 2 . This work not only provides a promising electrocatalyst for highly efficient HER in alkaline solution, but also offers a double-solvent strategy for the fabrication of various metal/carbon composites with uniform distribution of ultrafine metal nanoparticles.