Ming Li,Lili Guan,Yunshuo Zhu,Yanrui Shi,Yarong Huang,Xiwen Song
The phase formation and densification of LaCrO 3 were successfully achieved through AC reactive flash sintering (AC-RFS) in one step at a constant temperature of 600°C, using La 2 O 3 and Cr 2 O 3 as raw materials. The current density curve ‘buffer region’ was discovered under different electric field strengths. The ‘buffer region’ corresponds to the phase transformation from the intermediate phase La 2 CrO 6 to the target product LaCrO 3 . Joule heating and a high heating rate resulted in nearly full densification of the LaCrO 3 ceramic central region sintered for 1 second at maximum current density. In particular, the behavior of LaCrO 3 was analyzed, and the phase transformation completion point was evaluated based on the RFS behavior without the need for complex testing methods. The discovery of the ‘buffer region’ provides experimental guidance for determining the phase transformation completion points of various other materials in RFS experiments.
Peng Yu,Xiaojing Zhu,Xiaolan Wang,Shuangying Wang,Weiping Li,Guoxin Tan,Yu Zhang,Chengyun Ning
Rapid and effective bone mineralization at the bone/implant interface is required for successful orthopedic and dental implants. In this study, two periodic microscale functionalized zones on titanium (MZT) are created, namely, nanoneedle zones and buffer zones. The aim of this design is to provide spatially regulated topographical cues on titanium to enhance the efficacy of bone regeneration. This goal is achieved using a versatile and effective technique in which nanoneedle structures are hydrothermally constructed on the surface of titanium sheets, after which selective laser irradiation is used to construct buffer zones. The zonal structures of the MZT overcome the suppressive effect of the nanoneedle film on osteoblasts. Additionally, the MZT exhibits zone-selective apatite deposition and protein adsorption. The accelerated in vitro osteoblast differentiation and nodule deposition on the MZT are confirmed. Elemental analysis of the bone nodules formed by the osteoblasts growing on the titanium and MZT demonstrates they have different compositions. Histological and scanning electron microscope analysis of the bone formation on in vivo implants shows that this process is also enhanced by the MZT implant. The concept of constructing functionalized zones on titanium implant could facilitate future research on improving the design of orthopedic and dental implant surfaces.
Ag@Cu 2 O tandem catalysts is effective to improve the selectivity of hydrocarbons in CO 2 RR, where Ag core generates *CO intermediates, which migrate to Cu 2+ /Cu + interface, promoting proton transfer and C-C coupling forming *OCCHO. However, Cu + crucial for C-C coupling exhibits instability under reductive conditions. Herein, we used Ag@Cu 2 O tandem catalysts as a sacrificial template to synthesize Ag@Cu 2 O@Cu-BDC (BDC = 1,4-benzenedicarboxylic acid) tandem catalysts through an in-situ conversion strategy, which can not only introduce Cu 2+ , but also stabilize Cu + by forming a Cu-BDC MOF shell. In addition, by adjusting the amount of sacrificial template, the controllable regulation of Cu 2+ and Cu + content was successfully achieved, forming a Cu 2+ /Cu + valence state fluctuation buffer zone. It is found that this modulation not only significantly improve the selectivity towards hydrocarbons (CH 4 +C 2 H 4 ), but also enables the regulation of the reaction pathway, thereby allowing for fine-tuning of product selectivity. Notably, the Ag@Cu 2 O@Cu-BDC-5 tandem catalyst with a lower Cu 2+ /Cu + ratio demonstrated superior CH 4 selectivity (59.3 %), while the Ag@Cu 2 O@Cu-BDC-10 tandem catalyst with a higher Cu 2 ⁺/Cu + ratio achieved dominant C 2 H 4 production (43.0 %) under applied potential of −1.4 V vs. RHE for 20 h. This is attributed to Cu 2+ sites facilitated *CHO generation, while Cu + sites promoted C-C coupling as evidenced by the in-situ infrared and DFT calculations. Additionally, this study demonstrated the existence of a tandem catalysts that could increase the CO coverage on Cu sites, ensuring the full utilization of Cu + and Cu 2+ sites to further enhance product selectivity and reduce the overpotential for optimal product generation.
危险品化学品经营许可证（带存储）