Keywords MOF-derived; C-TiO2/CoTiO3; Core/shell; Type II heterojunction; Antibiotics removal Highlights * Core/shell C-TiO.sub.2/CoTiO.sub.3 type II heterojunction was synthesized by MOF-derived method. * C-TiO.sub.2/CoTiO.sub.3 shows excellent photocatalytic degradation and TOC removal of CIP. * The *OH is the main radical species in the photocatalytic degradation of CIP. * A new approach and insight for the synthesis of core/shell heterojunction was proposed. A novel core/shell C-TiO.sub.2/CoTiO.sub.3 type II heterojunction was successfully synthesized via a direct calcination method by using MIL-125/Co core-shell nanocakes as a sacrificial template and precursor. In the calcination process, the organic ligand in MIL-125 acts as an in-situ carbon doping source to form a carbon-doped TiO.sub.2 core (C-TiO.sub.2). At the same time, CoTiO.sub.3 nanoparticles are formed on the surface of C-TiO.sub.2 by an in-situ solid-state reaction between the C-TiO.sub.2 and Co.sup.2+ shell of MIL-125/Co. Due to such delicate core/shell structural features, carbon doping and type II heterojunctions, C-TiO.sub.2/CoTiO.sub.3 core/shell composites can effectively harvest visible light, facilitate the interfacial separation and suppress the recombination of photogenerated electron-hole pairs, leading to the remarkable photocatalytic activity for removal of ciprofloxacin (CIP). In particular, C-TiO.sub.2/CoTiO.sub.3-3 exhibits the best photocatalytic degradation activity of CIP with a degradation efficiency of 99.6% and a total carbon content removal percentage of 76% under visible-light illumination for 120 min. In addition, the proposed photocatalytic mechanism study illustrated that the main radical species in the photocatalytic degradation of CIP using C-TiO.sub.2/CoTiO.sub.3 as the photocatalyst is *OH. This work provides a new approach and insight for synthesizing core/shell heterojunction-based photocatalysts for various applications. Author Affiliation: (a) Institute of Environmental Research at Greater Bay, Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou 510006, China (b) Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangdong, China * Corresponding authors. Article History: Received 6 September 2020; Revised 22 November 2020; Accepted 23 November 2020 (miscellaneous) Editor: Prof. G. Lyberatos (footnote)1 BY Lin and SS Li contributed equally to this manuscript. Byline: Biyun Lin (a,b,1), Shanshan Li (a,1), Yannan Peng (a), Zhihong Chen chenzhihong1227@sina.com (a,*), Xin Wang xin.wang@ecs-scnu.org (b,*)