| The activity of nanozymes is highly dependent on many factors,such as size,shape and morphology,composition,surface modification as well as constructing complex or hybrids of nanozymes,etc.Among these,size of nanozymes is considered as one of the most important factors,determining the catalytic activity performance of nanozymes.The high surface area of smaller size nanozymes,which has greater surface-to-volume ratio to interact with the substrates,causes superior catalytic activity.However,with reduction in particle size,the nanozymes will be easily aggregated,and the durability and activity will be correspondingly worse.Therefore,synthesis strategy and engineering of nanozymes are fundamental challenges,and it should be given priority.In view of these challenges,this thesis attempts to synthesize a series of metal graphitic nanozymes via chemical vapor deposition(CVD)method.The obtained nanozymes are further used in biological and environmental fields.The chapters of the thesis are divided as follows:Chapter 1 introduces nanotechnology followed by a brief discussion on the methods for synthesizing nanomaterials,types and engineering of nanozymes and their applications in sensing and wastewater treatment,along with the outline of this Ph D thesis.Chapter 2 constructs a graphene encapsulated Ru nanocrystal(Ru@G)for colorimetric detection of glutathione(GSH).With a large surface area and abundant catalytic sites,Ru@G exhibits high POD-like activity,especially at neutral p H that allows it for a potential application in biological field.Based on this outstanding property,Ru@G nanozyme is applied for colorimetric sensor of GSH at near-physiological p H with a low LOD(～0.54μM),and the recoveries of GSH in human blood samples are ranging from 95.5%to 108.8%with RSD less than 4%.Chapter 3 synthesizes a graphene encapsulated Co Rh alloy(Co Rh@G)for biomarker sensing.The prepared Co Rh@G shows good stability in harsh environmental conditions such as extreme p H and high temperature.Importantly,Co Rh@G displays excellent POD-like activity and exhibits high affinity toward TMB oxidation with a small K_mvalue of about 0.028m M or 15 folds lower than HRP.These characteristics of Co Rh@G allow it with high precision and sensitivity for colorimetric sensors of variety biomarkers such as dopamine(DA)and ascorbic acid(AA)with good linear ranges and low limits of detections.Chapter 4 designs a graphene encapsulated Co Ru alloy(Co Ru@G)for environmental application.Benefiting from a large surface area,high resistance corrosion,good magnetic property,excellent catalytic activity,Co Ru@G is applied to remove organic dyes via physical adsorption and chemical degradation.The commonly used organic dyes in textile industry including,rhodamine B(Rh B,methyl blue(MB),rhodamine 6G(R6G),and methyl orange(MO)are selected as study model.The Co Ru@G shows excellent absorption of organic dyes at different p H and temperature as well as in real water samples.Importantly,due to their catalytic and absorption ability,Co Ru@G displays highly efficient removal of organic dyes via synergic degradation and absorption. |
