In Situ Composition-Transforming Fabrication of BiOI/BiOIO3 Heterostructure: Semiconductor p-n Junction and Dominantly Exposed Reactive Facets

We for the first time disclose the integrated effects of a semiconductor p-n heterojunction and dominantly exposed reactive facets that are enabled in a facile way. Unlike most of the reported semiconductor heterojunctions that are constructed by compositing the individual components, in this work, we report the composition transformation fabricating BiOI/BiOIO3 heterostructure via an in situ reduction route by using thiourea as the reducing agent. This reducing process enables BiOIO3 dominant exposure of the {010} reactive facet, and the exposed percentage can be effectively tuned by monocontrolling the thiourea concentration. The photocatalysis and photoelectrochemical properties of samples are assessed by surveying the decomposition of methyl blue (MB) and photocurrent generation under simulated solar light or visible light illumination. The leterostructured BiOI/BiOIO3 nanocomposites unfold drastically strengthened photoreactivity, in which the MB degradation rate is over 85% for 1 h irradiation, and the photocurrent density rises more than 3 times higher than the pristine sample. This enhancement should be ascribed to the formation of a steady p-n junction between the n-type BiOIO3 and p-type BiOI as well as dominantly exposed reactive facets. Separation and transfer of photoinduced charges are thereby greatly boosted as verified by the electrochemical and photoelectrochemical results. This work paves a novel way for fabrication of semiconductor p n junction via composition transformation and furnishes a new perspective into the designing of crystal reactive facet.