The Preparation And Photocatalytic Properties Of A CdS/Graphdiyne Composite And A Multinuclear Cobalt-Based Nanocatalyst

Water splitting and CO₂ reduction via photocatalysis have been regarded as effective pathways to settle down the issues of energy shortage and environmental pollution.However,the practical applications of these photocatalytic reactions require the design and development of high-performance photocatalysts,presenting a significant challenge.Up to date,several problems remains in the catalytic performances of photocatalysts.First,their relatively low stability leads to inefficient recyclability.Second,the severe recombination of electrons and holes brings about the modest utilization of light energy.Third,the introduction of noble metals significantly increases the expense of catalyst preparation.To solve these problems,we conducted the following studies:?1?the first work in this thesis shows the introduction of a novel carbon material,graphdiyne?GD?,into the photocatalytic systems for hydrogen evolution.Specifically,a CdS/GD heterojunction was prepared through a in situ simple growth process by adding Cd?AcO?₂ into a dimethyl sulfoxide?DMSO?solution containing GD substrate.The as-prepared CdS/GD heterojunction exhibits a much better performance for photocatalytic hydrogen evolution compared to that of pristine GD and CdS nanoparticles.The photocatalytic performance of CdS/GD heterostructure containing 2.5 wt%of GD?GD2.5?is2.6 times higher than that of the pristine CdS nanoparticles.The enhanced catalytic performance can be ascribed to the formation of CdS/GD heterojunction,in which the presence of GD can not only stabilize CdS nanoparticles by preventing the agglomeration of CdS nanoparticles but also act as a photogenerated hole transfer material for efficiently separating photogenerated electron-hole pairs in CdS.Accordingly,this work provides the potential of GD-derived materials for solar energy conversion and storage.?2?On the other hand,the excessive emission of CO₂ have resulted in destructive environmental problems,including global warming and climate anomalies.The transformation of CO₂ into value-added feedstocks can be a promising approach to solve the above issues.In this context,the second work of this thesis exhibits the preparation of a nano-catalyst for photocatalytic carbon dioxide reduction by simple mixing cobalt salts and an amine-rich polymer.The obtained catalyst inherits the advantages of heterogeneous catalyst,which exhibits easy separation,high stability,etc.In addition,the experimental results of photocatalytic carbon dioxide reduction indicate that a synergistic catalysis may contribute to the effectively enhanced activity of carbon dioxide reduction,and the production of carbon monoxide can be increased by 2.57 times,in contrast to a mononuclear cobalt complex which cannot catalyze the reaction in a synergistic manner.