Er3+, Yb3+ doping induced core–shell structured BiVO4 and near-infrared photocatalytic properties

•We report the design of core (BiVO4)–shell (BiVO4: Er3+, Yb3+) composite UC photocatalyst.•Valence spectra reveal the shell layer plays crucial roles in charge carrier mobilities.•Shell suppresses the recombination process, and leads to higher up-conversion performance.

It is commonly considered that the upconversion (UC) photocatalytic material is prepared by at least two steps which the first step is the synthesis of up-conversion fluorescent material, and then growth of the corresponding semiconductor on the fluorescent material. Herein, we report on the design and synthesis of core (BiVO4)–shell (BiVO4: Er3+, Yb3+) composite UC photocatalyst by in situ process. The novel features of the process are the mild operating conditions by a doping selection of Er3+, Yb3+. Using transmission electron microscopy (TEM), we found the composite is characteristic of monoclinic scheelite structure. Through X-ray photoelectron spectroscopy (XPS), it suggests that the photocatalyst comprised of core (BiVO4)–shell (BiVO4: Er3+, Yb3+). The presence of dopant (Er3+ and Yb3+) in the shell could suppress the radiative recombination process, leading to higher photon efficiency. Furthermore, photoactivities for near infrared (NIR)-light-driven photoelectrochemical (PEC) water splitting demonstrate that the photocatalytic performance of the Er/Yb co-doped BiVO4 (U08, 3.22 μA cm−2, 0.7 V vs. RHE) is about 7 times that of undoped BiVO4 (U0, 0.48 μA cm−2, 0.7 V vs. RHE). This enhancement was also proven by the elimination efficiency of RhB under the NIR illuminations. The valence spectra reveal that the shell layer photocatalyst plays crucial roles in enhancing charge carrier mobilities.

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