Hybridization of covalent organic frameworks and photosensitive metal-organic rings:A new strategy for constructing supramolecular Z-scheme heterostructures for ultrahigh photocatalytic hydrogen evolution

The rational design of Z-scheme heterojunction photosystems based on covalent organic frameworks(COFs)is a promising strategy for harnessing solar energy for hydrogen conversion.Herein,a direct Z-scheme single-atom photocatalyst based on COF and metal-organic ring has been constructed through the supramolecular interactions of coral-like COF(S-COF)and photosensitized Pd2L2 type metal-organic ring(MAC-FA1).The MAC-FA1/S-COF heterojunction exhibits good light absorption,efficient charge separation and transfer,slow electron-hole recombination,and highly dispersed Pd active sites,enabling an efficient and stable H_(2) evolution reaction.The optimized 4%MAC-FA1/S-COF achieves an H_(2) evolution rate of 100 mmol g^(−1)h^(−1)within 5 h and obtains a total accumulated turn-over number relative to Pd(TON_(Pd))of 437,685 within 20 h,far superior to S-COF,MAC-FA1,M-5/S-COF,Pd/S-COF,and M-5/Pd/S-COF,which is one of the highest records among COF-based photocatalysts for solar-driven H_(2)evolution.This is the first work to incorporate photosensitized metal-organic rings/cages into porous crystalline COFs to form a supramolecular Z-scheme heterojunction,which has significant potential as a high-performance photocatalyst for solar-driven H_(2)production.

A Power and Area Optimization Approach of Mixed Polarity Reed-Muller Expression for Incompletely Specified Boolean Functions

The power and area optimization of Reed-Muller （RM） circuits has been widely concerned. However, almost none of the exiting power and area optimization approaches can obtain all the Pareto optimal solutions of the original problem and are efficient enough. Moreover, they have not considered the don＇t care terms, which makes the circuit performance unable to be further optimized. In this paper, we propose a power and area optimization approach of mixed polarity RM expression （MPRM） for incompletely specified Boolean functions based on Non-Dominated Sorting Genetic Algorithm II （NSGA-II）. Firstly, the incompletely specified Boolean function is transformed into zero polarity incompletely specified MPRM （ISMPRM） by using a novel ISMPRM acquisition algorithm. Secondly, the polarity and allocation of don＇t care terms of ISMPRM is encoded as chromosome. Lastly, the Pareto optimal solutions are obtained by using NSGA-II, in which MPRM corresponding to the given chromosome is obtained by using a chromosome conversion algorithm. The results on incompletely specified Boolean functions and MCNC benchmark circuits show that a significant power and area improvement can be made compared with the existing power and area optimization approaches of RM circuits.