Chromium(Ⅵ) removal in a solar-driven photocatalytic fuel cell with carbon quantum dots modified p-type zinc-based metal−organic framework photocathode

High-efficiency photoelectrode played a significant role in photocatalytic fuel cell (PFC) systems. In this study, a zinc-based metal-organic framework modified by carbon quantum dots (N-Zn-MOF/CQDs) and the BiVO4 were respectively presented as the photocathode and photoanode of the PFC system toward Cr(Ⅵ) reduction. Various analytical techniques were utilized to characterize the physicochemical, optical and photoelectrochemical properties of the as-prepared samples. With the addition of CQDs, the visible-light response and charge separation rate were remarkably enhanced. In the PFC system, the circuit current density of 58.04 mA cm−2 and max power density of 1.35 mW cm−2 were achieved, which was superior to other reported PFC systems. Under optimized conditions, 100% Cr(Ⅵ) can be removed within 120 min of visible-light illumination. This work provided a new method to decorate the zinc-based metal−organic framework cathode to dramatically improve the photocatalytic performance.