Surface OH species on electrocatalysts play a pivotal role in affecting the hydrogen evolution reaction (HER). Herein, we highlight the critical role of surface OH basicity in regulating interfacial water structure and OH desorption behavior. By annealing Ru/Ni(OH) 2 at various temperatures, we successfully tailored the electronic state of surface OH species, with the catalyst annealed at 300 °C (Ru-Ni-300) exhibiting superior HER performance, achieving a current density of 100 mA/cm 2 at an exceptionally low overpotential of 71 mV. X-ray photoelectron spectroscopy demonstrates that the electron-rich surface OH species on Ru-Ni-300 exhibit strong Lewis basicity. The enhanced OH basicity facilitates the formation of hydrogen-bond networks with interfacial water through electron donation, which in turn promotes OH desorption kinetics. Quasi-in-situ XPS and density functional theory calculations further elucidated that the increased electron density on surface OH species reduces OH adsorption energy, thus accelerating HER performance. These findings unveil a direct correlation between surface OH basicity and HER efficiency, offering new insights into tailoring surface environments for advanced water-splitting electrocatalysts.
Bin Li,Feng-Fan Lu,Xiao-Wen Gu,Kai Shao,Enyu Wu,Guodong Qian
Developing efficient and stable water adsorbents for adsorption-driven heat transfer technology still remains a challenge due to the lack of efficient strategies to enhance low-pressure water uptakes. The authors herein demonstrate that the immobilization of Lewis basic nitrogen sites into metal–organic frameworks (MOFs) can improve water uptake and target benchmark coefficient of performances (COPs) for cooling and heating. They present the water sorption properties of a chemically stable MOF (termed as Zr-adip), designed by incorporating hydrophilic nitrogen sites into the adsorbent MIP-200. Zr-adip exhibits S-shaped sorption isotherms with an extremely high water uptake of 0.43 g g −1 at 303 K and P / P 0 = 0.25, higher than MIP-200 (0.39 g g −1 ), KMF-1 (0.39 g g −1 ) and MOF-303 (0.38 g g −1 ). Theoretical calculations reveal that the incorporated N sites can serve as secondary adsorption sites to moderately interact with water, providing more binding sites to strengthen the water binding affinity. Zr-adip achieves exceptionally high COPs of 0.79 (cooling) and 1.75 (heating) with a low driving temperature of 70 °C, outperforming MIP-200 (0.78 and 1.53) and KMF-1 (0.75 and 1.74). Combined with its ultrahigh stability, excellent cycling performance, and easy regeneration, Zr-adip represents one of the best water adsorbents for adsorption-driven cooling and heating.
Excessive CO 2 emissions and the resultant global warming present significant environmental challenges, posing threats to human health and public safety. Metal–organic frameworks (MOFs), known for their high specific area and large porosity, hold the promise for CO 2 capture. However, a major obstacle is the low loading mass of MOFs and the limited interface affinity and compatibility between MOFs and substrates. In this study, we present an electrospinning-assisted in-situ synthesis dual metallic framework strategy for preparing flexible Zn/Co-ZIF nanofibrous membranes (NFMs). This method achieves the high loading mass of MOFs and introduces abundant Lewis basic sites, thereby enhancing the CO 2 adsorption. The dual metallic Zn/Co-ZIF NFMs exhibit remarkable features, including high MOF loading mass (70.23 wt%), high specific surface area (379.63 m 2 g −1 ), large porosity (92.34 %), high CO 2 adsorption capacity (4.43 mmol/g), high CO 2 /N 2 adsorption selectivity (37), and high CO 2 /CH 4 adsorption selectivity (31). Moreover, the dual metallic Zn/Co-ZIF NFMs demonstrate robust structural stability and durability attributed to the excellent interface affinity between MOFs and NFMs, retaining 96.56 % of their initial capacity after 10 adsorption–desorption cycles. This work presents a prospective direction for developing flexible dual metallic MOF NFMs for the efficient capture of CO 2 .
危险品化学品经营许可证（带存储）