Enhanced Photoelectrocatalytic Water Splitting in Bi2Mo1-x W x O6 Solid Solutions: Understanding the Atomic Level Mechanism from the Experimental and First-Principles Approach

Thesecond-order Jahn-Teller distortion (SOJT-D) is predominantlyobserved in the MO6 octahedra of Aurivillius metal oxidessuch as Bi2MoO6 and Bi2WO6, due to the presence of both transition metal Mo6+ (orW(6+)) and Bi3+ lone-pair cations. This effectleads to intraoctahedral distortion as the consequence of the mixingof empty d-orbitals and completely filled p-orbitals of the ligandsthat may affect the efficiency of photocatalysts. Herein, photoelectrocatalytic(PEC) water splitting performance of second-order Jahn-Teller distortedBi(2)MoO(6), Bi2WO6, and Bi2Mo1-x W x O6 solid solutions is investigated by the combinedexperimental and first-principles approach. Our theoretical studyreveals that the SOJT-D parameter is monotonically decreased withincreasing x value of Bi2Mo1-x W x O6 solidsolutions, and this trend is well correlated with Raman analysis.The Bi2Mo1-x W x O6 (0 < x < 1)solid solutions show higher PEC activity as compared to both pristinematerials, as experienced from our study that the Bi2Mo0.9W0.1O6 photoanode delivered maximumefficiency, which is & SIM;4 and & SIM;17-fold higher than thatof Bi2MoO6 and Bi2WO6,respectively. In the presence of both Mo and W cations, the recombinationcenter of photoinduced charge carriers is suppressed due to theirdifferent conduction band levels and spatially separated, resultingin enhanced PEC water splitting activity in the solid solutions.