Applications Of Biomass-derived Carbon Nanomaterials In Electrochemical Sensors And Biofuel Cells

Carbon nanomaterials have attracted remarkable attention from the scientific community for their combinations of advantages chemical and physical properties,such as good electrical,excellent chemical stability and high mechanical strength,and exhibit widespread applications in material preparation,energy storage,biology and medical science.In the literature review of this article,the classification,methods of synthesis and applications of carbon nanomaterials are introduced in detail.Biomass is a widely sourced,low-cost,environmentally friendly and renewable carbon-rich organic material.Due to the advantages of large specific surface aera,porous structure and excellent chemical stability,biomass-derived carbon nanomaterials conform to the advocacy concept of green and sustainable development.In this article,we used a varety of biomass to prepare biomass-derived carbon nanomaterials with different morphologies and they were used to construct electrochemical sensors and biofuel cells(BFCs).The specific contents are as follows:(1)Kelp is used as the precursor for the preparation of kelp-derived hierarchical meso-macroporous carbons(K-d HMMCs)through the direct carbonization.Owing to the advantages(such as high specific area,the hierarchical meso-macroporous structure and high density of defective sites)of K-d HMMCs,the electrochemical sensing platform based on K-d HMMCs shows excellent electrocatalytic activities towards many electroactive molecules,such as hydrogen peroxide(H2O2),ascorbic acid(AA)and acetaminophen(APAP).In particular,compared with bare glassy carbon(GC)and carbon nanotubes(CNTs)modified GC(CNTs/GC)electrodes,the K-d HMMCs modified GC(K-d HMMCs/GC)electrode exhibits better electroanalytical performance for detection of H2O2 and AA,such as higher sensitivities and lower detection limits.The electrochemical sensing platform based on K-d HMMCs is also used to deteimine the levels of H2O2 or AA in real samples(such as human urine sample,AA injections and beverages)and the results acquired are satisfactory.(2)Sweet potatoes are served as precursors to synthesize a carbon aerogel with hierarchical meso-macroporous and branching nanostructure(HMM-BNCA).Compared with GC and CNTs/GC electrodes,HMM-BNCA modified GC(HMM-BNCA/GC)electrode exhibits more negative oxidation peak potential(-0.005 V),lower detection limit(0.45 ?M)and higher sensitivities for detection of AA.HMM-BNCA/GC electrode is also applied to determine the levels of AA in real samples(AA injection and beverage),indicating the feasibility of the electrochemical sensing platform based on HMM-BNCA in complex systems.(3)We developed a biosensor based on the lactate oxidase(LOD)and horseradish peroxidase(HRP)for the determination of lactate.The two enzymes are immobilized on the electrode modified by the three dimensional carbon nanoballs cross linked carbon aerogel(3D-CNBs CA)derived from sugarcane.The 3D-CNBs CA plays an important role in the direct electron transfer between the electroactive center of HRP and the electrode.Compared with the monoenzymatic lactate biosensor based on LOD,the bienzymatic lactate biosensor exhibits wider linear ranges and lower detection for detection of lactate.The bienzymatic lactate biosensor also exhibits good selectivity,repeatability,and stability.The bienzymatic lactate biosensor was also applied to assess the levels of lactate in compound lactic acid ointment and beverage,and the results were satisfactory.The results demonstrate the bienzymatic or multienzymatic biosensors hold broad application prospects in the future.(4)To enhance the power densities of BFCs applied in human body fluids,the bienzyme-based bioanode was fabricated using the glucose oxidase(GOD)and LOD for the oxidation of both glucose and lactate.Potato-derived carbon nanosphere aerogels(PCNAs)were used as the electrode modification materials for the bioanode.The maximum power density of glucose-lactate/O2 BFC was fabricated by the bienzyme-based bioanode is higher than that of glucose/O2 BFC or lactate/O2 BFC and can reach 82.2% of the total maximum power density of two BFCs in p H 7.0 phosphate buffer solution(PBS)containing glucose and lactate.The similar phenomena were observed in human sweat,urine and tears,which indicate that the glucose-lactate/O2 BFC achieved a substantial increase in power generation at low concentrations of biofuels without changing the number of BFCs.The study demonstrates that the enhancement of power densities is feasible by immobilizing bienzyme on bioanode with oxidizing mixtures of two fuels and exhibits a broad application prospect.(5)We designed a bienzyme-based bioanode that uses the alcohol oxidase(AOD)and GOD for the oxidation of ethanol and glucose.Pumkin stems-derived coral-like carbon aerogels(PSCCAs)with a large specific surface area were used as the electrode modification materials for bioanode.The electrochemical performance of the ethanol-glucose/O2 BFC assembled by the(AOD-GOD)-based bioanode was investigated in p H 7.0 PBS containing ethanol and glucose as well as two alcoholic beverages.The results demonstrate that the maximum power density of the ethanol-glucose/O2 BFC is higher than that obtained on the ethanol/O2 BFC or glucose/O2 BFC,whether in PBS containing two substrates or in two alcoholic beverages.The phenomenon exhibits that the ethanol-glucose/O2 BFC can achieve a substantial enhancement in power generation even using low-concentration real samples as biofuels without changing the number of BFCs.The study exhibits that multi-enzyme immobilized bioanode for BFCs may improve power output by oxidizing mixtures of biofuels in complex samples.