Self-Protonated Ho-Doped Zn(O,S) as a Green Chemical-Conversion Catalyst to Hydrogenate Nitro to Amino Compounds

Abstract

Zn(O,S) has been successfully doped with different amounts of Ho and characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and transient photocurrent (TPC). The as-prepared Ho-doped Zn(O,S) catalysts with different Ho amounts are evaluated for hydrogen evolution reaction. The catalyst with the best performance in evolving hydrogen is further utilized to hydrogenate 4nitrophenol (4-NP) to 4-aminophenol (4-AP). It is found that doping with Ho obviously enhanced charge transfer and photoresponse properties of the catalyst. Therefore, the modified Zn(O,S) can optimally evolve hydrogen by 18 624 μmol/g, which is 20% higher than that of pristine Zn(O,S). Subsequently, the in situ generated hydrogen ions on catalyst surfaces also play an important role as a hydrogen source to hydrogenate 4-NP to 4-AP without any reducing agents such as NaBH 4 , which is commonly used as a hydrogen source. As Ho is doped in the lattices of Zn(O,S), it acts not only to separate photocarriers and to enhance the charge transfer but also to shorten the diffusion time of nitrophenolate ions to catalyst surfaces for further photocatalytic hydrogenation reaction (PHR) process. A plausible PHR mechanism has been provided to elucidate the great performance of Ho-modified Zn(O,S) for photocatalytic hydrogenation.

Amorphous-Ni(OH)2 on a Vertically Grown Lamellar Ag-Modified MoSx Thin-Film Electrode with Surface Defects for Hydrogen Production in Alkaline Solutions

“…Figure f shows that the S 2p 3/2 and 2p 1/2 orbitals are observed at 163.19 and 163.33 eV, respectively, with a separation energy of 1.14 eV between them. The peak positions of S 2p agreed well with previous works. , The XPS compositional analysis is done based on the peak area in the high-resolution spectra of elements, and the results are shown in Table .…”

A reusable catalyst based on CuO hexapods and a CuO–Ag composite for the highly efficient reduction of nitrophenols

“…based materials have been proved achieving a great effect on hydrogenation of nitroaromatic compounds at ambient temperature. 14,15 As earth-abundant and inexpensive metal, Cu has been frequently investigated as alternative to rare metal materials, especially in catalysis. 16 Cu based nanomaterials are particularly attractive due to their improving catalytic activity effectively.…”

“…based materials have been proved achieving a great effect on hydrogenation of nitroaromatic compounds at ambient temperature. 14,15 …”

Environmentally Benign Photoreactions for Hydrogen Production and Cleavage of N═N bond in Azobenzene over Co-Doped Zn(O,S) Nanocatalyst: The Role of In Situ Generated H+

“…Meanwhile, for CZ-5 and CZ-10 nanocatalysts, Co might be precipitated on the catalyst surfaces due to the excess amount of Co, thus resulting in less effective doping of Co at the Zn cation site in the Zn(O,S) structure. 29 The diffractogram also confirmed that the as-prepared CZ-x nanocatalyst possessed no secondary phase.…”

“…Besides, it was found that the doping of Co at 2.5% induced the maximum shift, indicating the most optimum dopant amount of Co into the Zn­(O,S) lattice. Meanwhile, for CZ-5 and CZ-10 nanocatalysts, Co might be precipitated on the catalyst surfaces due to the excess amount of Co, thus resulting in less effective doping of Co at the Zn cation site in the Zn­(O,S) structure . The diffractogram also confirmed that the as-prepared CZ- x nanocatalyst possessed no secondary phase.…”