Construction of Frustrated Lewis Pairs in Poly(heptazine Imide) Nanosheets via Hydrogen Bonds for Boosting CO2 Photoreduction.

The creation of frustrated Lewis pairs on catalyst surface is an effective strategy for tuning CO2 activation. The critical step in the formation of frustrated Lewis pairs is the spatial effect of proximal Lewis acid-Lewis base pairs. Here, we demonstrate a facile surface functionalization methodology that enables hydrogen bonding between N and H atoms to mediate the construction of frustrated Lewis pairs in poly(heptazine imide), thereby increasing the propensity to activate CO2 molecules. Experimental and theoretical results show that the construction of active hydrogen bonding regions can facilitate the bending of CO2 molecules. Furthermore, the delocalization of electron clouds induced by the hydrogen bonding-mediated frustrated Lewis pairs can promote the heterolytic cleavage and photocatalytic conversion of CO2. This work highlights the potential of utilizing hydrogen bonding-mediated strategy in heterogeneously photocatalytic activation of CO2 over polymer materials.

The design of a linear voltage divider based on metal oxide arresters.

In recent years, linearization technology for nonlinear devices has become a hot topic in many fields. In this study, a linear voltage divider based on metal oxide arresters was designed by combining linearization technology and electrical measurement technology to solve the objective problems of online voltage monitoring. These problems include high difficulty in equipment installation, low measurement accuracy, and poor economic benefits. Based on a summary of linearization theory, the sufficient and necessary conditions for the linearization of the voltage divider were deduced in detail. The relevant circuit simulations were conducted, along with voltage divider experiments under power frequency AC voltage, operating overvoltage, and lightning overvoltage. The results revealed that the voltage divider was able to realize linearized measurements and meet the relevant standards of online voltage monitoring. The measurement errors were concentrated in the transition region between the pre-breakdown region (small current region) and the breakdown region (nonlinear region) in the volt-ampere characteristic curve. The main influencing factor of errors was the consistency of the nonlinear characteristics of the high- and low-voltage arms of the voltage divider. The voltage divider designed in this study can be applied in many scenarios, such as power plants, substations, high-voltage electrical equipment manufacturing plants, and high-voltage laboratories.