2D/2D Ultrathin Co Nanosheets/CeVO₄ Nanobelts@PDA with a Strong Electronic Interaction and Broadband Light Harvesting for Efficient Photocatalytic H₂ Evolution from Ammonia Borane

Abstract

The activity of supported photocatalysts closely depends on the number of exposed active sites, electronic interaction between active components and supports, and light harvesting capacity of catalysts. Herein, we report an effective approach to construct a photocatalyst Co/CeVO4 with abundant active sites and strong electronic interaction by regulating materials morphology and constructing a large 2D/2D contact interface, which is composed of ultrathin Co nanosheets and CeVO4 nanobelts, which shows greatly enhanced photocatalytic performance for H2 production from ammonia borane (NH3BH3). Furthermore, polydopamine (PDA) is introduced in the catalysts by forming a strong electronic interaction with CeVO4 nanobelts to broaden the light absorption range. Benefiting from the unique structure, the Co/CeVO4@PDA-37 exhibits excellent photocatalytic activity with a total turnover frequency value of 115.38 min–1. Structure characterizations indicate the excellent catalytic performance for Co/CeVO4@PDA caused by the strong electronic interaction between Co and CeVO4 due to special morphology and broadband light harvesting owing to the introduction of PDA. In addition, the activity of the catalyst remained almost unchanged after five cycles. Therefore, this work not only paves new avenues for the facile synthesis of photocatalysts with high catalytic performance but also provides the design for broadband light harvesting of photocatalysts for H2 evolution from NH3BH3.

Hydrophilic amorphous Cr2O3 supported Co species toward efficient hydrogen production from ammonia borane under visible light irradiation

“…S6†), suggesting the formation of amorphous Co species which is consistent with previous reports. 37 Additionally, the broad peak around 45° assigned to Co can further confirm the existence of amorphous Co. 38 BET surface area of Cr 2 O 3 -F-0.5 was calculated to be 246.2512 m 2 g −1 which is smaller than Co/Cr 2 O 3 -F-0.5 (296.8048 m 2 g −1 ) (Fig. S7 and S8†).…”

Highly electron-deficient ultrathin Co nanosheets supported on mesoporous Cr2O3 for catalytic hydrogen evolution from ammonia borane

“…The surface charge of Cr 2 O 3 with oxygen vacancies has a positive zeta potential, which can produce small electrostatic repulsion with positively charged Co 2+ in solution, leading to the formation of highly dispersed ultrathin Co nanosheets with the assistance of NaBH 4 , in agreement with literature reports. 28…”

“…The surface charge of Cr 2 O 3 with oxygen vacancies has a positive zeta potential, which can produce small electrostatic repulsion with positively charged Co 2+ in solution, leading to the formation of highly dispersed ultrathin Co nanosheets with the assistance of NaBH 4 , in agreement with literature reports. 28 In order to demonstrate the universality of the strategy that decreasing the metal surface electron density can achieve enhanced activity of supported catalysts under visible light irradiation, Ni species with a similar work function to Co was selected as the active component supported on Cr 2 O 3 for NH 3 BH 3 hydrolysis. Meanwhile, Ni-without Cr 2 O 3 and sample with different supports also were tested for comparison.…”

“…10 In addition, in our previous study we found that the support with oxygen vacancies was prone to forming ultrathin metal nanosheets which not only exposed more active sites and improved the utilization efficiency of the metal, but also further regulated the electron density of the metal by improving the contact area and constructing strong metal–support interactions between the active metal and the support. 28 Inspired by the above considerations, loading ultrathin active metal nanosheets on Cr 2 O 3 is a promising method to understand the structure–property relationship of catalysts with a decreased electron density of active metals in the NH 3 BH 3 hydrolysis process.…”