Photo-assisted electrocatalysis of black phosphorus quantum dots/molybdenum disulfide heterostructure for oxygen evolution reaction

Molybdenum Disulfide (MoS2), as a typical two-dimensional (2D) material, has abundant reserves and unique electronic structures. However, the limited number of active sites severely hinders its application in electrocatalytic oxygen evolution reaction (OER). Black phosphorus quantum dots (BP QDs), with large exposed surface areas and a mass of active edge sites, are suitable for loading on MoS2 nanosheets to form type-II heterojunctions, resulting in additional active sites and higher mobility, thereby improving the OER performance of MoS2. In addition, photo-assistance was applied to reduce high energy barriers and the energy loss, thus improving the overall efficiency of energy conversion. Here, BP QDs and MoS2 nanosheets were prepared by liquid phase exfoliation and mixed-dimensional BP QDs/MoS2 heterojunctions were constructed. The experimental results show that the BP QDs/MoS2 heterojunctions have been successfully synthesized and the OER performance of the heterojunctions outperform pure MoS2 and BP QDs, with lower onset potentials and Tafel slope. Meanwhile, both photo-assistance and changing KOH concentration can adjust the OER performance of BP QDs/MoS2 heterojunction. Furthermore, the as-prepared heterojunctions demonstrated strong stability in KOH aqueous solution. This work identifies that constructing BP QDs/MoS2 heterojunctions and photo-assistance are effective strategies to facilitate the electrocatalytic OER performance.