Tailor-Made Core–Shell CaO/TiO₂–Al₂O₃ Architecture as a High-Capacity and Long-Life CO₂ Sorbent

CaO-based sorbents are widely used for CO₂ capture, steam methane reforming, and gasification enhancement, but the sorbents suffer from rapid deactivation during successive carbonation/calcination cycles. This research proposes a novel self-assembly template synthesis (SATS) method to prepare a hierarchical structure CaO-based sorbent, Ca-rich, Al₂O₃-supported, and TiO₂-stabilized in a core–shell microarchitecture (CaO/TiO₂–Al₂O₃). The cyclic CO₂ capture performance of CaO/TiO₂–Al₂O₃ is compared with those of pure CaO and CaO/Al₂O₃. CaO/TiO₂–Al₂O₃ sorbent achieved superior and durable CO₂ capture capacity of 0.52 g CO₂/g sorbent after 20 cycles under the mild calcination condition and retained a high-capacity and long-life performance of 0.44 g CO₂/g sorbent after 104 cycles under the severe calcination condition, much higher than those of CaO and CaO/Al₂O₃. The microstructure characterization of CaO/TiO₂–Al₂O₃ confirmed that the core–shell structure of composite support effectively inhibited the reaction between active component (CaO particles) and main support (Al₂O₃ particles) by TiO₂ addition, which contributed to its properties of high reactivity, thermal stability, mechanical strength, and resistance to agglomeration and sintering

One-Step Synthesis of CuO–Cu₂O Heterojunction by Flame Spray Pyrolysis for Cathodic Photoelectrochemical Sensing of l‑Cysteine

CuO–Cu₂O heterojunction was synthesized via a one-step flame spray pyrolysis (FSP) process and employed as photoactive material in construction of a photoelectrochemical (PEC) sensing device. The surface analysis showed that CuO–Cu₂O nanocomposites in the size less than 10 nm were formed and uniformly distributed on the electrode surface. Under visible light irradiation, the CuO–Cu₂O-coated electrode exhibited admirable cathodic photocurrent response, owing to the favorable property of the CuO–Cu₂O heterojunction such as strong absorption in the visible region and effective separation of photogenerated electron–hole pairs. On the basis of the interaction of l-cysteine (l-Cys) with Cu-containing compounds via the formation of Cu–S bond, the CuO–Cu₂O was proposed as a PEC sensor for l-Cys detection. A declined photocurrent response of CuO–Cu₂O to addition of l-Cys was observed. Influence factors including CuO–Cu₂O concentration, coating amount of CuO–Cu₂O, and applied bias potential on the PEC response toward l-Cys were optimized. Under optimum conditions, the photocurrent of the proposed sensor was linearly declined with increasing the concentration of l-Cys from 0.2 to 10 μM, with a detection limit (3S/N) of 0.05 μM. Moreover, this PEC sensor displayed high selectivity, reproducibility, and stability. The potential applicability of the proposed PEC sensor was assessed in human urine samples