Construction of Z-scheme heterojunction (ZCH) is one of the most effective ways to enhance photocatalytic performance of photocatalysts. The direct all-solid-state p-n ZCH shows the best prospect, but its fabrication mechanism, especially function of the interfacial electric field (IEF) was rarely expounded explicitly. Herein, a direct all-solid-state p-n copper indium disulfide/tungsten oxide (CIS/WO) ZCH was prepared through a facile hydrothermal process for the first time. The CIS/WO ZCH exhibits enhanced photocatalytic activity because of significantly accelerated photogenerated charge separation via a Z-scheme charge migration process. The Z-scheme charge transfer pathway is inferred from matched energy band levels of CIS and WO and the IEF is confirmed to play a key role. The CIS/WO ZCH can fast produce singlet oxygen via hole oxidation of superoxide radicals under visible light irradiation, while pure CIS and WO cannot, effectively verifying the Z-scheme charge transfer process. This work illustrates the principle for fabrication of the direct all-solid-state p-n ZCH and function of the IEF, as well as provides a new ZCH. (C) 2019 Elsevier Inc. All rights reserved.