Manipulating the Optically Active Defect–Defect Interaction of Colloidal Quantum Dots for Carbon Dioxide Photoreduction
Mengke Cai, Xin Tong, Peisen Liao, Shujie Shen, Hongyang Zhao, Xin Li, Xia Li, Huaqian Zhi, Nan Zhou, Ziqian Xue, Lei Jin, Jieyuan Li, Guangqin Li, Fan Dong, Andrei V. Kabashin, Zhiming M. Wang
Abstract
Defect engineering in colloidal quantum dots (QDs), a typical photocatalytic material, is promising to tailor optoelectronic properties and achieve solar-to-fuel energy conversion. However, understanding the effect of defect–defect interactions on both charge carrier and catalytic dynamics is still challenging. Here, we report a class of defect-engineered copper-deficient Zn-doped CuInS 2 (ZCIS) QDs that synergistically utilize copper vacancy and Cu 2+ defect states to realize CO 2 photoreduction. Steady and transient optical characterizations reveal that the density of copper vacancy can manipulate the distribution of optically active Cu + and Cu 2+ defect states (appearing as Cu In ″ and Cu Cu • species, respectively), wherein the Cu + defect states suppress interband absorption and sharpen the Shockley–Read–Hall recombination, while Cu 2+ defect states enable the prolonged exciton lifetime of QDs. In situ infrared spectroscopic investigation and theoretical density functional calculation demonstrate the photoactive Cu 2+ defect states nearby the copper vacancy in ZCIS QDs can effectively activate CO 2 to the COOH* intermediates, leading to a remarkable photocatalytic CO production rate up to 532.3 μmol g –1 h –1 (turnover number ∼1963) after 120 h illumination.