Nadia Gholampour

Catalytic hydrogenation of CO₂ into CH₄ is an effective method to convert waste CO₂ and green hydrogen into clean fuel on a large scale. However, the viability of such process largely relies on the development of highly active heterogeneous catalysts. Here, a tailored methanation catalyst, Co nanoparticles immobilized into a highly porous N‐doped carbon matrix, is prepared by the carbonization of a cobalt‐based layered zeolitic imidazolate framework (ZIF−L) material under an argon atmosphere. This catalyst displays a specific activity of 22.3 mol_CH4/g_cat.min at 350 °C, significantly outperforming a similar catalyst derived from the more conventional ZIF‐67 (11.7 mol_CH4/g_cat.min). This is explained by the stabilization of small Co nanoparticles (∼20 nm) and by the presence of abundant medium‐strength basic sites related to the nitrogen doping in the catalyst prepared from ZIF−L. Notably, the new catalyst shows high stability; no deactivation is observed up to 60 hours on stream.

In this work, we excited as-spun wet films of PEDOT:PSS by ultrasonic vibration with varying frequency and power. This is a low-cost and facile technique for tailoring the structural and surface characteristics of solution-processed thin films and coatings. We deposited the coatings on both rigid and flexible substrates and performed various characterization techniques, such as atomic force microscopy (AFM), scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), transmittance, electrical conductivity, and contact angle measurements, to understand how the ultrasonic vibration affects the coating properties. We found that as a result of ultrasonic vibration, PEDOT:PSS sheet conductivity increases up to five-fold, contact angle of water on PEDOT:PSS increases up to three-fold, and PEDOT:PSS roughness on glass substrates substantially decreases. Our results affirm that ultrasonic vibration can favor phase separation of PEDOT and PSS and rearrangement of PEDOT-rich charge transferring grains. In addition to providing a systematic study on the effect of ultrasonic frequency and power on the film properties, this work also proves that the ultrasonic vibration is a novel method to manipulate and tailor a wide range of properties of solution-processed thin films, such as compactness, chain length and arrangement of polymer molecules, conductivity, and surface wettability. This ultrasonication method can serve organic, printed and flexible electronics.