基于煤气化细渣构建碳基氧还原催化剂及其催化性能研究

Preparation and properties of carbon-based electrocatalysts from gasification fine slag for oxygen reduction

气化细渣是煤气化过程产生的一种含碳量较高的固体废弃物。经炭灰分离得到的高炭是制备炭材料的潜在碳源。本研究以气化细渣浮选-酸洗后的高炭为前驱体,通过高温活化制备了氮掺杂碳基催化剂,结合拉曼光谱、XPS和SEM等表征,探究了活化剂比例和氮源对催化剂理化特性的影响,揭示了两者与催化剂氧还原性能的内在关联,验证了气化细渣作为原料制备碳基氧还原催化剂的可行性。结果表明,随着活化剂KOH比例的增加,碳基催化剂的氧还原催化性能先增加后减小,当高炭和KOH质量比为1∶4时其催化性能最优。此外,相较于氯化铵,以三聚氰胺作为氮源具有更强的氮掺杂效应,使得CKN_(6)-143催化剂的起始电位可达0.87 V(vs.RHE),极限扩散电流密度为4.95 mA/cm^(2),平均电子转移数为3.82,表现出良好的电催化性能,为气化细渣的高值化利用奠定了基础。

Gasification fine slag is a kind of solid waste with high carbon content produced in coal gasification process.The residual carbon obtained by carbon ash separation is a potential carbon source for preparing high quality carbon materials.In this study,the carbon residue after flotation of fine gasification slag was used as the precursor to prepare N-doped carbon-based electrocatalysts through high temperature activation.Combined with the characterization of Raman spectroscopy,XPS and SEM,the influence of activator ratio and nitrogen source on the physical and chemical structure of the catalyst was explored.The intrinsic relationship between activation formula and oxygen reduction performance of catalyst was revealed.The feasibility of preparing carbon-based electrocatalysts with gasification fine slag as raw material was verified.The results demonstrate that the oxygen reduction catalytic performance of carbon materials increases first and then decreases with the increase of the proportion of KOH.The optimal catalytic performance was achieved when the mass ratio of carbon residue to KOH was 1:4.In addition,melamine has stronger nitrogen doping effect as a nitrogen source than NH_(4)Cl,making the initial potential of CKN_(6)-143 up to 0.87 V(vs.RHE),the limiting current density is 4.95 mA/cm^(2),and the average electron transfer number is 3.82,indicating that CKN_(6)-143 has good electrocatalytic performance.The results provide a possibility for preparing oxygen reduction catalyst with gasification fine slag.