Dataset Information

In situ Raman spectroscopy reveals the structure evolution and lattice oxygen reaction pathway induced by the crystalline-amorphous heterojunction for water oxidation.

ABSTRACT: One of the most successful approaches for balancing the high stability and activity of water oxidation in alkaline solutions is to use amorphous and crystalline heterostructures. However, due to the lack of direct evidence at the molecular level, the nano/micro processes of amorphous and crystalline heterostructure electrocatalysts, including self-reconstruction and reaction pathways, remain unknown. Herein, the Leidenfrost effect assisted electrospray approach combined with phase separation was used for the first time to create amorphous NiO _x /crystalline α-Fe₂O₃ (a-NiO _x /α-Fe₂O₃) nanowire arrays. The results of in situ Raman spectroscopy demonstrate that with the increase of the potential at the a-NiO _x /α-Fe₂O₃ interface, a significant accumulation of OH can be observed. Combining with XAS spectra and DFT calculations, we believe that more OH adsorption on the Ni centers can facilitate Ni²⁺ deprotonation to achieve the high-valence oxidation of Ni⁴⁺ according to HSAB theory (Fe³⁺ serves as a strong Lewis acid). This result promotes the electrocatalysts to follow the lattice oxygen activation mechanism. This work, for the first time, offers direct spectroscopic evidence for deepening the fundamental understanding of the Lewis acid effect of Fe³⁺, and reveals the synergistic effect on water oxidation via the unique amorphous and crystalline heterostructures.

SUBMITTER: Dong J

PROVIDER: S-EPMC9116351 | biostudies-literature | 2022 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

<i>In situ</i> Raman spectroscopy reveals the structure evolution and lattice oxygen reaction pathway induced by the crystalline-amorphous heterojunction for water oxidation.

Dong Jianing J Qian Zhengxin Z Xu Pan P Yue Mu-Fei MF Zhou Ru-Yu RY Wang Yanjie Y Nan Zi-Ang ZA Huang Siying S Dong Quanfeng Q Li Jian-Feng JF Fan Feng Ru FR Tian Zhong-Qun ZQ

Chemical science 20220422 19

One of the most successful approaches for balancing the high stability and activity of water oxidation in alkaline solutions is to use amorphous and crystalline heterostructures. However, due to the lack of direct evidence at the molecular level, the nano/micro processes of amorphous and crystalline heterostructure electrocatalysts, including self-reconstruction and reaction pathways, remain unknown. Herein, the Leidenfrost effect assisted electrospray approach combined with phase separation was ...[more]

PMID: 35694335

Similar Datasets

Project description:Ammoniacal thiosulfate has been used lately as an alternative lixiviant for leaching gold from sulfides ores which are not amenable for cyanidation. However, the oxidation of the sulfide minerals generates products that inhibit the dissolution of gold and can promote the degradation of the leaching solution. The complexity of the ammoniacal thiosulfate leaching system has prevented the unification and clarification of the mechanisms of oxidation of sulfide ores used for gold extraction. In this study, a method combining polarization curves, Electrochemical impedance spectroscopy (EIS), and in situ Raman spectroscopy was implemented to investigate the oxidation process of high-purity pyrite. Pyrite samples were dispersed in carbon paste electrode (CPE-Py). The polarization curves of CPE-Py exhibited an increase in current values for overpotentials greater than 0.1 V, indicating the initiation of mineral oxidation processes. Subsequently, a maximum current was observed initially, followed by subsequent decrease, indicating the occurrence of passivation processes on the electrode surface. Hydrodynamic polarization curves demonstrated that the overpotential at which the passivation process occurs is independent of mass transport, suggesting that the passivation products were formed through solid-state transformation. Impedance spectra revealed that at overpotentials below 0.1 V, a partially resolved capacitive semicircle was observed, which was associated with the resistance encountered when charge was transferred between the solution and the surface layer interface. This resistance decreased as the polarization overpotential increased, implying a decrease in charge transfer kinetics. At higher overpotentials (0.3 V-0.4 V), a second capacitive semicircle appeared, linked to the oxidation of one or several species present in the mineral. In situ Raman spectroscopy was utilized to identify the oxidation species of pyrite in ammonia-thiosulfate ((NH4)2S2O3) leaching solution at a pH = 10.2. The composition of the species varied depending on the applied anodic potential. At low anodic potentials (0.1 V), Fe(OH)2 and thiosulfate (S2O32-) were formed, while at high anodic potentials (0.4 V), iron products such as Fe3O4 and γ-FeOOH, as well as sulfide species including thiosulfate, tetrathionates and sulfates (S2O32-, S4O6-2 and SO42-) were formed.

Dataset Information

In situ Raman spectroscopy reveals the structure evolution and lattice oxygen reaction pathway induced by the crystalline-amorphous heterojunction for water oxidation.

Publications

<i>In situ</i> Raman spectroscopy reveals the structure evolution and lattice oxygen reaction pathway induced by the crystalline-amorphous heterojunction for water oxidation.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets