CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Meng Li,Ying Gu,Yajun Chang,Xiaocong Gu,Jingqi Tian,Xiang Wu,Ligang Feng
Water splitting plays an important role in overcoming the intermittent problems for sustainable energy development, and an efficient non-noble catalyst is highly desired to catalyze the more sluggish half-reaction of oxygen evolution reaction (OER). Herein, we demonstrated the Fe-doped CoF 2 as a novel and efficient catalyst for OER via facile structural transformation derived from the CoFe layered double hydroxide. The crystal structure and surface chemical state analysis indicated the successful structural transformation from CoFe layered double hydroxide to the bulk crystal of CoF 2 doped by Fe. The obtained Fe-CoF 2 nanoflakes largely improved the utilization of active sites and effectively promoted mass transfer. The Fe-CoF 2 -300 showed a low overpotential of 230 mV to achieve the current density of 10 mA cm −2 when loaded on an inert glass carbon electrode, which is about 60 mV less than that of the pristine CoFe layered double hydroxide catalyst. It also exhibited a small Tafel slope of 41.9 mV dec -1 and super catalytic stability. High valence state change from the M−F bond to the M−O bond driven by the OER process was indicated after the long-term stability test indicating the facile active phase formation. This works provides an effective doping strategy to design novel catalysts for decreasing the overpotential and accelerating the kinetics of OER.
研究领域:
材料科学
·
能源化学
✓ 已验证
DOI
高影响因子
Inorganic Chemistry Frontiers
·
2022
·Vol. 10
·期 3
·804-814
·
IF 7.779
Hu Yao,Yinan Zheng,Siliang Yue,Songjie Hu,Wenyu Yuan,Xiaohui Guo
The oxygen evolution reaction (OER) has slow chemical dynamics in the electrochemical decomposition of water. Herein, we demonstrate that B-site substitution engineering on ABF3 is an efficient strategy to boost the OER activity due to the modified electronic structure. A series of perovskite fluorides with the formula NaCo1−2xFexNixF3 were fabricated via a simple hydrothermal process, in which Co was partially substituted by both Fe and Ni. The optimized perovskite fluoride exhibited a low overpotential of 265 mV at a current density of 10 mA cm−2 and outstanding electrochemical stability after 100 h continuous electrocatalysis for the OER. These results are superior to the state-of-the-art perovskite-based OER catalysts. The X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) results showed that the dual-substitution of Fe and Ni atoms not only produced higher valence Co3+ ions but also generated the more active species Fe3+. In addition, the produced metal oxyhydroxides (MOOH, M = Co, Fe, Ni) on the catalyst surface during OER activation could contribute both excellent catalytic activity and ultralong stability.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Engineering Materials
·
2024
·
IF 0
Bin Qiao,Jing Zhang,Xuhui Li,Xingming Ning,Zhongwei An,Xinbing Chen,Yu Chen,Pei Chen
The rational design and control of active sites are essential for achieving a highly active and stable electrocatalyst. Herein, we report a bifunctional oxygen electrocatalyst, nanocrystals of CoF2-inserted carbon nanofibers, which was prepared by electrospinning and a subsequent fluorination process. Due to the large specific surface area and hierarchical porous structure, carbon nanofibers provide rapid mass transfer and expose more active sites for electrocatalytic oxygen reactions. The surface-oxidized CoF2 nanocrystals show high electroactivity for both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in alkaline solution, marked by up to 0.822 V of the ORR half-wave potential and as low as 370 mV of the OER overpotential. Benefiting from the excellent electrocatalysis activity, this material exhibits an excellent application prospect in rechargeable zinc-air batteries. As an air electrode catalyst, it can endow the zinc-air battery with a high specific capacity (871.2 mAh g–1), a large power density (124.30 mW cm–2), and excellent stability (120 h continuous charge/discharge), dramatically outperforming that of commercial Pt/C and RuO2 electrocatalysts. Density-functional theory (DFT) calculations indicate that surface oxygen atoms on CoF2 play a key role in enhancing the activity of Co atoms by p-d orbital hybridization. This work provides a perspective for designing bifunctional oxygen electrocatalysts urgently needed by rechargeable zinc-air batteries.
研究领域:
材料科学
·
电化学
·
能源技术
✓ 已验证
DOI
CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Zong Liu,Hui Liu,Xiaocong Gu,Ligang Feng
Surface engineering for the active phase of metal (oxy)hydroxide species formation in the oxygen-evolution reaction (OER) catalysts is significant for water splitting reaction in hydrogen fuel generation. Herein, we demonstrate the OER efficiently catalyzed by a novel quasi-single-crystalline cobalt fluoride, and reveal its surface structure evolution during the OER process that is instructive for catalysis process understanding and novel catalysts design. Because of strong ionic bonding dissociation driven by the chemical and electrochemical conditions, the structural evolution can readily generate such an active phase during the OER process. The X-ray photoelectron spectroscopy, in-situ Raman spectrum and microscopic observation confirm the structure evolution from pure cobalt fluoride to cobalt oxy/hydroxide over their surface, and the chemical anionic reconstruction induced cobalt oxy/hydroxide passive layer formation. The 3D nanoflower nanostructure can efficiently expose more active sites and increase mass transportation by expanding the contact surface to the electrolyte. Remarkably, no activation is required to reach stable catalytic performance. It only needs an overpotential as low as 285 mV to afford 10 mA cm −2 with a small Tafel slope of 60 mV dec -1 , outperforming the state-of-the-art IrO 2 catalyst and some analogs transitional metal-based catalyst. It also shows excellent stability. The current findings are instructive in understanding OER catalytic reaction and active Co-based catalysts fabrication.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
ChemNanoMat
·
2022
·Vol. 8
·期 6
·e202200085
·
IF 3.82
Yang Gu,Chuqian Meng,Shuyue Dong,Hexin Zhu,Qian Liu,Yonglan Luo,Qingquan Kong,Tingshuai Li
High-performance earth-abundant electrocatalysts for oxygen evolution reaction (OER) are highly desirable. In this report, we successfully synthesized amorphous Fe−P shell electrodeposited on Co(OH)F nanowire arrays supported on titanium mesh (Fe−P@Co(OH)F/TM) as an efficient catalyst for OER. Such catalyst exhibits excellent OER activity with a low overpotential of 267 mV to reach the geometrical current density of 10 mA cm −2 in 1.0 M KOH. In addition, it has good electrochemical durability to maintain its activity for at least 20 h.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
ENERGY & FUELS
·
2022
·
IF 4.654
Yujie Wang,Mingyu Zhang,Yuxuan Zhang,Yafeng Wang,Wenxin Liu,Chujie Yang,Veniamin Kondratiev,Feixiang Wu
Metal fluoride–lithium batteries have been viewed as very promising candidates for next-generation rechargeable batteries with higher energy densities. However, the intrinsic insulating properties of metal fluoride cathode lead to the poor reaction kinetics and unsatisfactory electrochemical performance. Herein, a honeycombed CoF2@C nanocomposite with a high specific surface area up to 180.4 m2 g–1, in which the nanosized CoF2 particles with size of 5–25 nm are evenly embedded in the honeycombed carbon framework, is prepared by the low-temperature fluorination of honeycombed Co@C nanocomposite precursor. As expected, the as-produced CoF2@C nanocomposite can deliver a high-capacity utilization of 365 mAh g–1 and an average capacity retention of 81.9% over 300 cycles at a current density of 110 mA g–1, as well as a reasonable capacity of 205 mAh g–1 at 1100 mA g–1. Such excellent electrochemical performance is due to the unique configuration that achieves the nanoconfinement of conversion reaction in the metal fluoride cathode. To be specific, on the one hand, the honeycombed structure provides uniformly isolated nanospace to inhibit the volume expansion and product agglomeration in the conversion reaction. On the other hand, the excellent reaction kinetics is attributed to the three-dimensional electron and ion conduction pathway, that is, the electrons are conducted through the honeycombed carbon walls, while Li+ are transferred via the interconnected honeycomb channels, facilitating the high-capacity utilization.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
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