Load transfer engineering via synergy of BiOI heterojunction with Ag and loading cocatalyst of La2O2CO3 in photoelectrochemical water splitting

Abstract

Photoelectrochemical water splitting of bismuth oxyiodide, BiOI is of special interest for solar energy utilization. Herein, a novel photoanode designed by compositing BiOI with Ag and loading lanthanum oxy-carbonate, La2O2CO3 as a cocatalyst for oxygen evolution reaction. This design not only decreases the onset potential besides increases the photocurrent and stability. The Ag–BiOI photoanode exhibits an enhancement of 2.5 fold in the photocurrent density compared to BiOI. The maximum photocurrent density of the Ag–BiOI photoanode is achieved for the Ag amount of 1.2 %. The photoelectrocatalytic performance of Ag–BiOI is outstandingly further enhanced after loading the La2O2CO3 layer. The photocurrent density of 0.17 mA cm−2 is attained for Ag–BiOI/La2O2CO3 photoanode with respect to BiOI (0.06 mA cm−2) at 1.23 V vs RHE indicating its high capability for photoelectrochemical water splitting. The photo-potential of Ag–BiOI/La2O2CO3 photoanode (632 mV) is 6.9 and 2.5 times more than BiOI and Ag–BiOI, respectively resulting in the highest degree of band bending and the excellent trapping capability for electrons which leads to the enhancement in the separation and transfer of photo-induced charge carriers. Ag–BiOI/La2O2CO3 photoanode indicates a smaller arc radius in the Nyquist plot compared to those of BiOI, Ag–BiOI, and BiOI/La2O2CO3 photoanodes.