甲醛气体在ZnO表面光降解的机理研究

摘要

本文采用溶胶-凝胶法制备纳米氧化锌粒子,并对其降解气相甲醛的光催化活性进行研究.研究发现,在紫外光照射下,当水或氧气存在时,氧化锌可以将甲醛氧化生成二氧化碳;但是在两种不同气氛条件下的反应过程是不同的.气相水参与反应的过程中,首先是水分子被光活化生成羟基自由基,然后再与甲醛进行反应;而在氧气参与反应的过程中,是光活化的氧直接与甲醛反应,这一步骤在氧气参与的甲醛光催化降解反应中占据主导地位.这一反应机理的发现,对研究甲醛的光催化降解可能具有重要意义.%Nanosized ZnO particles have been synthesized by sol-gel method and studied for photocatalytic activities toward gaseous CH2O degradation.It was found that CH2O adsorbed on ZnO nanoparticles can be oxidized to CO2 under UV light irradiation with the coexistence of either O2 or H2O.However,different from aqueous condition where H2O molecules are first oxidized to be free radicals then react with CH2O,direct photoactivation of O2 becomes the dominant step in promoting photocatalytic degradation efficiency of gaseous CH2O.The results reveal a new reaction mechanism that can be important for further modification of photocatalyst for gaseous CH2O degradation.