General approach for atomically dispersed precious metal catalysts toward hydrogen reaction

As a carbon-free energy carrier,hydrogen has become the pivot for future clean energy,while efficient hydrogen production and combustion still require precious metal-based catalysts.Single-atom catalysts(SACs)with high atomic utilization open up a desirable perspective for the scale applications of precious metals,but the general and facile preparation of various precious metal-based SACs remains challenging.Herein,a general movable printing method has been developed to synthesize various precious metal-based SACs,such as Pd,Pt,Rh,Ir,and Ru,and the features of highly dispersed single atoms with nitrogen coordination have been identified by comprehensive characterizations.More importantly,the synthesized Pt-and Ru-based SACs exhibit much higher activities than their corresponding nanoparticle counterparts for hydrogen oxidation reaction and hydrogen evolution reaction(HER).In addition,the Pd-based SAC delivers an excellent activity for photocatalytic hydrogen evolution.Especially for the superior mass activity of Ru-based SACs toward HER,density functional theory calculations confirmed that the adsorption of the hydrogen atom has a significant effect on the spin state and electronic structure of the catalysts.

Engineering Ruthenium-Based Electrocatalysts for Effective Hydrogen Evolution Reaction

The investigation of highly effective,durable,and cost-effective electrocatalysts for the hydrogen evolution reaction(HER)is a prerequisite for the upcoming hydrogen energy society.To establish a new hydrogen energy system and gradually replace the traditional fossil-based energy,electrochemical water-splitting is considered the most promising,environmentally friendly,and efficient way to produce pure hydrogen.Compared with the commonly used platinum(Pt)-based catalysts,ruthenium(Ru)is expected to be a good alternative because of its similar hydrogen bonding energy,lower water decomposition barrier,and considerably lower price.Analyzing and revealing the HER mechanisms,as well as identifying a rational design of Ru-based HER catalysts with desirable activity and stability is indispensable.In this review,the research progress on HER electrocatalysts and the relevant describing parameters for HER performance are briefly introduced.Moreover,four major strategies to improve the performance of Ru-based electrocatalysts,including electronic effect modulation,support engineering,structure design,and maximum utilization(single atom)are discussed.Finally,the challenges,solutions and prospects are highlighted to prompt the practical applications of Rubased electrocatalysts for HER.

Financial performance evaluation and forecasting of enterprises by the combination of PCA and CNN deep learning

1 Introduction Financial evaluation focuses on pursuing sustainable financial development under the“New Normal”of China’s economy.It is of great practical significance to explore innovative methods based on established financial evaluation indexes and systems[1,2].The joint strategy of PCA methods and Deep Learning models seems to have a scientific basis and a good fusion mechanism in earlier studies[3-5].The innovation of our research is to combine evaluation method,unsupervised learning,with supervised learning.Based on the PCA method,the selected data is dimensionally reduced and comprehensively scored,then the unsupervised learning K-means clustering method is used to divide the sample into five evaluation levels according to the performance score.Finally,combined with the Convolutional Neural Network(CNN)framework,the company’s financial performance can be profiled and predicted.On one hand,the theoretical significance of this study is to combine the traditional PCA method with the Deep Learning method to predict the performance level for the performance portrait of enterprises.