Rationally Designed CeO₂ Nanosheets over Co₉S₈ Nanoparticles form S‐Scheme Heterojunction for Efficient Hydrogen Production

Abstract

Enriching the active sites of catalysts and artificially regulating the directional migration of photogenerated carriers are effective means to improve the catalytic activity of photocatalysts. In this work, CeO2 nanosheets are prepared by calcination at high temperatures, and the S‐scheme heterojunction photocatalyst CeO2@Co9S8 is prepared by coupling the Co9S8 nanoparticles prepared by hydrothermal method on CeO2 nanosheets. The large specific surface area of CeO2 nanosheets provides sufficient loading sites for Co9S8 and Co9S8 nanoparticles can effectively disperse with the help of CeO2 nanosheet structure, which effectively inhibits the agglomeration of nanoparticles. The high photosensitivity of Co9S8 increases the utilization of CeO2@Co9S8 S‐scheme heterojunction to visible light. The construction of S‐scheme heterojunction improves the separation efficiency of photogenerated carriers, prolongs the service life of photogenerated charges, retains the photogenerated electrons and holes with strong reduction and oxidation ability in the catalyst system, and improves the performance of photocatalytic hydrogen production. The hydrogen yield of 15 wt% Co9S8 supported CeO2@Co9S8 can reach 15.7 times CeO2 and 2.5 times Co9S8, and the composite catalyst has good stability. This work provides a new way for adjusting the surface structure and carrier behavior of photocatalysts.

Study on Water Splitting of the 214-Type Perovskite Oxides LnSrCoO4 (Ln = La, Pr, Sm, Eu, and Ga)

“…Moreover, the 3d 5/2 (3d 3/2) rare-earth elements La, Pr, Sm, Eu, and Gd appear in the XPS spectra at 835.02 (851.92), 933.38 (954.13), 1083.28 (1110.49), 1134.62 (1164.16), and 1187.26 (1219.84) eV (Figure S14), respectively, which is consistent with previous reports. ,− In the Co 2p spectra (Figure (b)), the characteristic peaks of Co 3+ in LaSrCoO 4 are located at 780.60 eV (Co 3+ 2p3/2) and 795.80 eV (Co 3+ 2p1/2), while the peaks of Co 2+ are located at 782.48 eV (Co 2+ 2p3/2) and 797.68 eV (Co 2+ 2p1/2). In addition, the satellite peaks of Co 2p3/2 and Co 2p1/2 are located at 789.50 and 804.90 eV, respectively. − The Co 2p spectra of PrSrCoO 4 , SmSrCoO 4 , EuSrCoO 4 , and GaSrCoO 4 perovskite oxide catalysts exhibit very similar line shape, and the peak positions of 2p3/2 and 2p1/2 of their Co elements are listed in Table S3. The binding energies of Co ions with the same valence state and atomic states from LnSrCoO 4 are very similar (Table S3), which is attributed to the approximate identical crystal field environment where Co atoms are located.…”

Co3O4@SnO2/graphdiyne type-II heterojunction and p–n heterojunction jointly enhance photocatalytic hydrogen production: Co–O–Sn bond as a bridge for electron transfer

“…Therefore, the decrease of light intensity has an adverse effect on the photocatalytic efficiency, resulting in a decrease in hydrogen production. 42…”

“…Therefore, the decrease of light intensity has an adverse effect on the photocatalytic efficiency, resulting in a decrease in hydrogen production. 42 The pH of the solution exerts a substantial inuence on the photocatalytic reaction, especially in the electron-donating dyesensitized system. This is mainly because pH directly affects the state of dyes and electron donors, both of which are important components of the system.…”