scholarly journals Role of Pr-Vacancies and O-Interstitials on the Activity and Stability of (Pr1-xLnx)2NiO4 (Ln = La, Nd, Pm, Sm, Gd, Tb, Dy, and Ho) towards Oxygen Reduction Reactions: A DFT Study

2021 ◽  
Author(s):  
Yanxing Zhang ◽  
Wei Wang ◽  
Yudong Wang ◽  
Nengneng Xu ◽  
guang tian ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Oxygen Reduction ◽  
Density Functional ◽  
Normal Mode Analysis ◽  
Reduction Reaction ◽  
Mode Analysis ◽  
Additional Energy ◽  
Ion Migration ◽  
Oxygen Ion Migration ◽  
Praseodymium Nickelate

Abstract Praseodymium nickelate, Pr2NiO4 (PNO), is a promising electrode to promote oxygen reduction reaction (ORR) in a solid oxide fuel cell, but it exhibits phase transformation during electrochemical operation. The origins of the simultaneous phase transformation and high electrochemical performance still remain obscure. We carried out a systematic density functional theory study to elucidate the mechanism for this conjugated phenomenon. Both electronic structure/charge and normal-mode analysis suggest the presence of peroxide. Our study shows that the formation of peroxide (O22-) is attributed to both oxygen interstitials and Pr vacancies. The peroxide species limits the oxygen ion migration due to the additional energy required to break its O-O bond, which leads to a decrease in ORR activity. Subsequently, we investigate the diffusion paths of Pr-ions while comparing them with those of other Ln3+ ions (La, Nd, Pm, Sm, Gd, Tb, Dy, and Ho) in PNO. The formation energies for various Ln3+ cation occupancies are calculated, as well as segregation energies in CeO2(111) surfaces. Finally, criteria for effective Ln3+ dopants are developed. La, Nd, and Pm are proposed as potential substituents in PNO to obtain a stable structure.

scholarly journals Probing the activity of transition metal M and heteroatom N4 co-doped in vacancy fullerene (M–N4–C64, M = Fe, Co, and Ni) towards the oxygen reduction reaction by density functional theory

RSC Advances ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 3174-3182
Author(s):  
Siwei Yang ◽  
Chaoyu Zhao ◽  
Ruxin Qu ◽  
Yaxuan Cheng ◽  
Huiling Liu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Transition Metal ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Density Functional ◽  
Reduction Reaction ◽  
Functional Theory ◽  
Co Doped

In this study, a novel type oxygen reduction reaction (ORR) electrocatalyst is explored using density functional theory (DFT); the catalyst consists of transition metal M and heteroatom N4 co-doped in vacancy fullerene (M–N4–C64, M = Fe, Co, and Ni).

scholarly journals Highly active and selective oxygen reduction to H2O2 on boron-doped carbon for high production rates

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yang Xia ◽  
Xunhua Zhao ◽  
Chuan Xia ◽  
Zhen-Yu Wu ◽  
Peng Zhu ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Density Functional ◽  
High Selectivity ◽  
Density Functional Theory Calculations ◽  
Reduction Reaction ◽  
Production Rates ◽  
Practical Applications ◽  
Highly Active ◽  
Boron Doped ◽  
Oxidized Carbon

AbstractOxygen reduction reaction towards hydrogen peroxide (H2O2) provides a green alternative route for H2O2 production, but it lacks efficient catalysts to achieve high selectivity and activity simultaneously under industrial-relevant production rates. Here we report a boron-doped carbon (B-C) catalyst which can overcome this activity-selectivity dilemma. Compared to the state-of-the-art oxidized carbon catalyst, B-C catalyst presents enhanced activity (saving more than 210 mV overpotential) under industrial-relevant currents (up to 300 mA cm−2) while maintaining high H2O2 selectivity (85–90%). Density-functional theory calculations reveal that the boron dopant site is responsible for high H2O2 activity and selectivity due to low thermodynamic and kinetic barriers. Employed in our porous solid electrolyte reactor, the B-C catalyst demonstrates a direct and continuous generation of pure H2O2 solutions with high selectivity (up to 95%) and high H2O2 partial currents (up to ~400 mA cm−2), illustrating the catalyst’s great potential for practical applications in the future.

Density functional theory study of oxygen reduction reaction on Pt/Pd3Al(111) alloy electrocatalyst

2016 ◽  
Vol 18 (21) ◽  
pp. 14234-14243 ◽  
Author(s):  
B. B. Xiao ◽  
X. B. Jiang ◽  
Q. Jiang
Keyword(s):  
Density Functional Theory ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Density Functional ◽  
Reduction Reaction ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Intensive Research

Developing efficient catalysts for the oxygen reduction reaction (ORR) to reduce cathode Pt loading without sacrificing the performance has been under intensive research.

scholarly journals Atomically Dispersed Fe-N4 Modified with Precisely Located S for Highly Efficient Oxygen Reduction

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Yin Jia ◽  
Xuya Xiong ◽  
Danni Wang ◽  
Xinxuan Duan ◽  
Kai Sun ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Density Functional ◽  
Catalytic Performance ◽  
Reduction Reaction ◽  
Edge Structure ◽  
Onset Potential ◽  
Local Environments ◽  
Half Wave ◽  
Reaction Performance ◽  
Specific Configuration

AbstractImmobilizing metal atoms by multiple nitrogen atoms has triggered exceptional catalytic activity toward many critical electrochemical reactions due to their merits of highly unsaturated coordination and strong metal-substrate interaction. Herein, atomically dispersed Fe-NC material with precise sulfur modification to Fe periphery (termed as Fe-NSC) was synthesized, X-ray absorption near edge structure analysis confirmed the central Fe atom being stabilized in a specific configuration of Fe(N3)(N–C–S). By enabling precisely localized S doping, the electronic structure of Fe-N4 moiety could be mediated, leading to the beneficial adjustment of absorption/desorption properties of reactant/intermediate on Fe center. Density functional theory simulation suggested that more negative charge density would be localized over Fe-N4 moiety after S doping, allowing weakened binding capability to *OH intermediates and faster charge transfer from Fe center to O species. Electrochemical measurements revealed that the Fe-NSC sample exhibited significantly enhanced oxygen reduction reaction performance compared to the S-free Fe-NC material (termed as Fe-NC), showing an excellent onset potential of 1.09 V and half-wave potential of 0.92 V in 0.1 M KOH. Our work may enlighten relevant studies regarding to accessing improvement on the catalytic performance of atomically dispersed M-NC materials by managing precisely tuned local environments of M-Nx moiety.

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