Fig. 1
From: Nanoscale imaging of charge carrier transport in water splitting photoanodes
Photoconductive AFM on BiVO4 photoanodes. a Schematic illustration of the photoconductive atomic force microscope (pc-AFM) setup. The BiVO4 film is illuminated from the FTO side through the transparent glass substrate. The bias voltage (Vs) is applied between the metal-coated probe and the transparent FTO back electrode. b Schematic illustrations of the relative energetic levels of FTO, BiVO4, and metal-coated probes. The solid lines indicate the vacuum level Evac, and the valence and the conduction band edge of BiVO4 (EC,BVO and EV,BVO). The dashed lines show the Fermi level of FTO (EF,FTO), BiVO4 (EF,BVO), and Au-coated and PtIr-coated probes (EF,Au, and EF,PtIr). The arrows indicate the work function of FTO (ΦFTO), the electron affinity of BiVO4 (χBVO), and the work function of Au-coated (ΦAu) and PtIr-coated probes (ΦPtIr). c Topography of BiVO4 thin film. d Dark current map is acquired with a PtIr-coated probe at an applied bias of 1.75 V. Corresponding photocurrent maps of the same area are acquired with a PtIr-coated probe (e) and an Au-coated probe (f) at an applied bias of 1.75 V and 1.45 V, respectively. The scale bar is 200 nm
