Innovative multifunctional hybrid photoelectrode design based on a ternary heterojunction with super-enhanced...

Electrochemical cells for direct conversion of solar energy to electricity (or hydrogen) are one of the most sustainable solutions to meet the increasing worldwide energy demands. In this report, a novel and highly-efficient ternary heterojunction-structured Bi₄O₇/Bi_3.33(VO₄)₂O₂/Bi₄₆V₈O₈₉ photoelectrode is presented. It is demonstrated that the combination of an inversion layer, induced by holes (or electrons) at the interface of the semiconducting Bi_3.33(VO₄)₂O₂ and Bi₄₆V₈O₈₉ components, and the rectifying contact between the Bi₄O₇ and Bi_3.33(VO₄)₂O₂ phases acting afterward as a conventional p-n junction, creates an adjustable virtual p-n-p or n-p-n junction due to self-polarization in the ion-conducting Bi₄₆V₈O₈₉ constituent. This design approach led to anodic and cathodic photocurrent densities of + 38.41 mA cm^-2 (+ 0.76 V_RHE) and- 2.48 mA cm^-2 (0 V_RHE), respectively. Accordingly, first, this heterojunction can be used either as photoanode or as photocathode with great performance for artificial photosynthesis, noting, second, that the anodic response reveals exceptionally high: more than 300% superior to excellent values previously reported in the literature.