Quinoline ramifications possess a wide range of biological activities and potential pharmacological activities. Here, a concept of bifunctional solid acid photocatalyst TiO2/AC/SO3H with high acid density is firstly purposed for efficiently pure green synthesis of 2-quinoline carboxamide under ultraviolet-visible light irradiation. After sulfonation, the acid density of TiO2/AC is markedly larger than that of sole TiO2 or AC, and the maximum yield of 2-quinoline carboxamide of 39% is obtained when the acid density of catalyst reaches 1.55 mmol/g. The new concept of bifunctional catalysis using solid acid and photocatalyst is potential for industrial application and instructive in green organic synthesis reactions which need radical and acid simultaneously. (c) 2016 Elsevier B.V. All rights reserved.