Xi'an Jiaotong University Gao Chuanbo&Suzhou University Hong Tao's team NC paper: Electron deficiency B promotes the valence state of Ni in single-layer NiFeBHydroxide nanosheets to achieve high-efficiency oxygen evolution
【Article information】
promotes the valence state of nickel in single-layer Nickel iron Boron hydroxide nanosheets to achieve high-efficiency oxygen evolution
First author: Bai Yuke, Wu Yu
Corresponding author: Gao Chuanbo, Cheng Tao
Unit: Xi'an Jiaotong University , Soochow University
[Research background]
In order to deal with the world's energy crisis and environmental pollution, it is particularly important to seek efficient clean energy production. As one of the important ways to produce ultrapure hydrogen on a large scale, electrolyzed water and hydrogen production is an important part of the future renewable energy industry production. However, the efficiency of electrolyzing water is largely limited by the oxygen evolution reaction (OER) that occurs on the anode. OER is a slow chemical reaction process involving four electron transfer, which usually requires the application of a higher overpotential to drive the progress of the reaction, resulting in severe electrical energy loss. Therefore, developing efficient oxygen evolution reaction catalysts is an important way to reduce the cost of hydrogen production by electrolyzing water.
transition metal hydroxide is considered to be the optimal catalyst for oxygen evolution reaction under basic conditions. In the oxygen evolution reaction, the transition metal evolved into a high-valent species and became the active center of OER. At present, research still lacks effective regulation of the process of forming the species at high price in transition metals, which is an important scientific problem faced in the design of this catalyst in .
[Article Introduction]
In response to this problem, Professor Gao Chuanbo's team of Xi'an Jiaotong University and Professor Cheng Tao's team of Soochow University published a research paper titled "Promoting nickel oxidation state transitions in single-layer NiFeB hydroxide nanosheets for efficient oxygen evolution" in the internationally renowned journal Nature Communications.
This work develops a nickel valence state evolution regulation strategy based on boron doping. It utilizes the inherent electron deficiency of boron to promote the valence state evolution process of the electron loss in the center of nickel, so that high-valence active species (Ni3+δ OOH) can be formed under low potential, thereby significantly improving the OER performance of nickel ferrohydroxide catalysts. Raman spectroscopy, X-ray absorption spectroscopy and electrochemical tests confirm that boron element plays a key role in the valence evolution of nickel. density functional theory calculations confirm the electron interaction between boron and nickel. Based on this principle, the NiFeB hydroxide nanosheets synthesized by the team can achieve an OER current density of 100 mA cm−2 at a 252 mV overpotential, which is significantly better than the catalytic performance of most nickel-based catalysts reported to date. This study provides theoretical guidance for the design and implementation of highly efficient OER catalysts.
Figure 1. Schematic diagram of the synthesis, catalytic properties and mechanism of NiFeB hydroxide electrolytic OER catalyst
[Big points of this article]
Key points 1: Synthesis and characterization of single-layer NiFeB hydroxide
Under room temperature, NiFeB alloy nanoparticles were hydrolyzed in situ to synthesize a single-layer hydroxide nanosheet. The thickness of the single-layer nanosheet is about 0.5 nm, which is equivalent to the octahedral monolayer of metal hydrogen oxide MO6 (M = Ni, Fe). X-ray diffraction (XRD) shows peaks located at ~34° and 60° (2θ), corresponding to the (100) and (110) planes of the MO6 octahedral monolayer. No diffraction peaks from the MO6 superposition sheet were observed in XRD, indicating that the nanosheets were composed of MO6 monolayers.
Figure 2. Synthesis and characterization of NiFeB hydroxide nanosheets. (a) Synthesis flowchart. (b) TEM diagram. (c) EDS of Ni, Fe and B. (d) XRD diagram. (e) B 1s XPS spectrum. Xi'an Jiaotong University Gao Chuanbo&Suzhou University Hong Tao's team NC paper: Electron deficiency B promotes the valence state of Ni in single-layer NiFeBHydroxide nanosheets to achieve high-efficiency oxygen evolution 【Article information】 promotes the valence state of nickel in single-layer Nickel iron Boron hydroxide nanosheets to achieve high-efficiency oxygen evolution
First author: Bai Yuke, Wu Yu
Corresponding author: Gao Chuanbo, Cheng Tao
Unit: Xi'an Jiaotong University , Soochow University
[Research background]
In order to deal with the world's energy crisis and environmental pollution, it is particularly important to seek efficient clean energy production. As one of the important ways to produce ultrapure hydrogen on a large scale, electrolyzed water and hydrogen production is an important part of the future renewable energy industry production. However, the efficiency of electrolyzing water is largely limited by the oxygen evolution reaction (OER) that occurs on the anode. OER is a slow chemical reaction process involving four electron transfer, which usually requires the application of a higher overpotential to drive the progress of the reaction, resulting in severe electrical energy loss. Therefore, developing efficient oxygen evolution reaction catalysts is an important way to reduce the cost of hydrogen production by electrolyzing water.
transition metal hydroxide is considered to be the optimal catalyst for oxygen evolution reaction under basic conditions. In the oxygen evolution reaction, the transition metal evolved into a high-valent species and became the active center of OER. At present, research still lacks effective regulation of the process of forming the species at high price in transition metals, which is an important scientific problem faced in the design of this catalyst in .
[Article Introduction]
In response to this problem, Professor Gao Chuanbo's team of Xi'an Jiaotong University and Professor Cheng Tao's team of Soochow University published a research paper titled "Promoting nickel oxidation state transitions in single-layer NiFeB hydroxide nanosheets for efficient oxygen evolution" in the internationally renowned journal Nature Communications.
This work develops a nickel valence state evolution regulation strategy based on boron doping. It utilizes the inherent electron deficiency of boron to promote the valence state evolution process of the electron loss in the center of nickel, so that high-valence active species (Ni3+δ OOH) can be formed under low potential, thereby significantly improving the OER performance of nickel ferrohydroxide catalysts. Raman spectroscopy, X-ray absorption spectroscopy and electrochemical tests confirm that boron element plays a key role in the valence evolution of nickel. density functional theory calculations confirm the electron interaction between boron and nickel. Based on this principle, the NiFeB hydroxide nanosheets synthesized by the team can achieve an OER current density of 100 mA cm−2 at a 252 mV overpotential, which is significantly better than the catalytic performance of most nickel-based catalysts reported to date. This study provides theoretical guidance for the design and implementation of highly efficient OER catalysts.
Figure 1. Schematic diagram of the synthesis, catalytic properties and mechanism of NiFeB hydroxide electrolytic OER catalyst
[Big points of this article]
Key points 1: Synthesis and characterization of single-layer NiFeB hydroxide
Under room temperature, NiFeB alloy nanoparticles were hydrolyzed in situ to synthesize a single-layer hydroxide nanosheet. The thickness of the single-layer nanosheet is about 0.5 nm, which is equivalent to the octahedral monolayer of metal hydrogen oxide MO6 (M = Ni, Fe). X-ray diffraction (XRD) shows peaks located at ~34° and 60° (2θ), corresponding to the (100) and (110) planes of the MO6 octahedral monolayer. No diffraction peaks from the MO6 superposition sheet were observed in XRD, indicating that the nanosheets were composed of MO6 monolayers.
Figure 2. Synthesis and characterization of NiFeB hydroxide nanosheets. (a) Synthesis flowchart. (b) TEM diagram. (c) EDS of Ni, Fe and B. (d) XRD diagram. (e) B 1s XPS spectrum.
Point 2: The regulatory effect of boron doping on nickel valence state evolution
The valence state evolution process of Ni under different overpotentials was explored through Raman spectroscopy and X-ray absorption spectrum (electrolyte: 1.0 M KOH of O2 saturated). Raman spectroscopy shows that a clear Ni3+δ OOH active species peak appears at 66 mV in B-doped NiFe hydroxide nanosheets, while this peak only occurs when the overpotential is higher than 266 mV. X-ray absorption spectrum shows that in B-doped NiFe hydroxide nanosheets, the valence state conversion overpotential range of nickel is 66-236 mV; while in NiFe hydroxide nanosheets without B, the valence state conversion overpotential range of nickel is 236-366 mV. These spectral results confirm that B doping significantly reduces the overpotential required for Ni2+ to evolve into active Ni3+δ.
Figure 3. Effect of B on the evolution of Ni valence state. The Raman spectrum and X-ray absorption spectrum of NiFeB hydroxide nanosheets (a,c) and NiFe hydroxide nanosheets (b,d) under different overpotentials.
Key points three: Catalytic performance evaluation
was tested in O2 saturated 1.0 M potassium hydroxide . Single-layer NiFeB hydroxide nanosheets can reach an OER current density of 100 mA cm−2 under 252 mV overpotential, and the catalytic activity is significantly higher than that of NiFe hydroxide nanosheets and is better than the catalytic performance of most nickel-based catalysts reported so far. The oxidation process of Ni species was studied by differential pulse voltammetry (DPV), indicating that B-doped NiFe hydroxide will cause a negative deviation of 60 mV in the starting potential of the Ni oxidation peak, which once again confirmed the promoting effect of B on Ni valence evolution. NiFeB hydroxide nanosheets also show high stability in OER, and can maintain stable operation for more than 130 hours at a constant current density of 10, 100 and 500 mA cm−2.
Figure 4. Electrochemical OER performance. (a) OER polarization curve. (b) Comparison of current density at 1.53 V. (c) Comparison with other nickel-based catalysts. (d) DPV curve. (e) EIS curve. (f) Catalytic stability test.
Key points 4: Mechanism study
DFT calculation shows that after B is introduced, the OER speed-decision step moves backward, and the energy barrier of the speed-decision step is significantly reduced, which is the main reason for the improvement of OER performance. After the introduction of B, the Ni valence state near B increased, with a net charge of Bader of +0.06, confirming that there is a strong electron interaction between B and Ni. Density of state (DOS) analysis showed that the 3d orbit of Ni and Fe was near the Fermi energy level, indicating that Ni and Fe are the centers of reactivity. DFT results support the critical role of B in improving the performance of Ni-based hydroxide OER.
Figure 5. DFT calculation results. (a) Free energy map of OER reaction intermediates. (b) Electronic local density function graph.
[Article link]
Promoting nickel oxidation state transitions in single-layer NiFeB hydroxide nanosheets for efficient oxygen evolution
https://www.nature.com/articles/s41467-022-33846-0
[Profile of the first author]
Bai Yuke : 2018 received a bachelor's degree in engineering from Central South University. Now . The Institute of Frontier Science and Technology of Xi'an Jiaotong University . Professor Gao Chuanbo's research team is studying for a doctorate degree. The research direction is the study of nanoscale metal-non-metal interactions and their catalytic properties.
Wu Yu : Graduated from the School of Materials, Yancheng Institute of Technology in 2019, and obtained a master's degree in engineering from Suzhou University in 2022. The research directions are CO2 electrical reduction, lithium metal battery theoretical simulation, etc.
[ Corresponding Author Introduction]
Professor Gao Chuanbo : In 2009, he received a doctorate in applied chemistry from Shanghai Jiaotong University and a doctorate in structural chemistry from Stockholm University in Sweden. In 2010, he went to , the University of California, Riverside, to engage in postdoctoral research.In September 2012, he returned to China to work and served as a professor, doctoral supervisor, and research team leader of the Institute of Frontier Science and Technology of Xi'an Jiaotong University. Selected as the "Xi'an Jiaotong University Youth Outstanding Talent Support Program" and Zhongying Young Scholar.
published 76 papers in Chem Rev, Chem, Nat Commun, JACS, Angew Chem, Nano Lett and other international authoritative academic journals (59 one or communications, 4 were selected as ESI highly cited papers, and 2 were selected as ESI hot topic papers). The SCI citations were more than 4,100 times, and the h index was 36. Selected as the "New Researcher" of the 2018 Royal Chemistry Association, Elsevier 2020 "Chinese Highly Cited Scholar". The research results have been reported by academic organizations and media such as the International Society of Optoelectronic Engineering (SPIE), Materials Views China, " Science and Technology Daily ", " China Science and Technology Daily ".
Project group homepage: http://gaochuanbo.gr.xjtu.edu.cn.
Professor Cheng Tao : From 2007 to 2012, he received his bachelor's, master's and doctoral degrees from Shanghai Jiaotong University. From 2012 to 2015, he was engaged in postdoctoral research at the California Institute of Technology in the United States. From 2015 to 2018, he served as a research scientist at the Joint Research Center for Photosynthesis (California Polytechnic Branch). In November 2018, he joined , the Institute of Functional Nano and Soft Matter of Soochow University, and was hired as a professor and doctoral supervisor. In the past five years, he has been mainly engaged in theoretical research on the intersection of theoretical chemistry and energy catalysis. Develop theoretical simulation calculation methods and apply them to important electrochemical reactions related to energy, including reaction mechanism research, material properties prediction and design of advanced functional materials. To date, more than 120 SCI papers have been published. Some articles were published in Nat. Catal., Nat. Chem. Proc. Natl. Acad. Sci. USA, J. Am. Chem. Soc., J. Phys. Chem. Lett., et al. . Research group homepage: https://tcheng-suda.github.io.
In September 2012, he returned to China to work and served as a professor, doctoral supervisor, and research team leader of the Institute of Frontier Science and Technology of Xi'an Jiaotong University. Selected as the "Xi'an Jiaotong University Youth Outstanding Talent Support Program" and Zhongying Young Scholar. published 76 papers in Chem Rev, Chem, Nat Commun, JACS, Angew Chem, Nano Lett and other international authoritative academic journals (59 one or communications, 4 were selected as ESI highly cited papers, and 2 were selected as ESI hot topic papers). The SCI citations were more than 4,100 times, and the h index was 36. Selected as the "New Researcher" of the 2018 Royal Chemistry Association, Elsevier 2020 "Chinese Highly Cited Scholar". The research results have been reported by academic organizations and media such as the International Society of Optoelectronic Engineering (SPIE), Materials Views China, " Science and Technology Daily ", " China Science and Technology Daily ".
Project group homepage: http://gaochuanbo.gr.xjtu.edu.cn.
Professor Cheng Tao : From 2007 to 2012, he received his bachelor's, master's and doctoral degrees from Shanghai Jiaotong University. From 2012 to 2015, he was engaged in postdoctoral research at the California Institute of Technology in the United States. From 2015 to 2018, he served as a research scientist at the Joint Research Center for Photosynthesis (California Polytechnic Branch). In November 2018, he joined , the Institute of Functional Nano and Soft Matter of Soochow University, and was hired as a professor and doctoral supervisor. In the past five years, he has been mainly engaged in theoretical research on the intersection of theoretical chemistry and energy catalysis. Develop theoretical simulation calculation methods and apply them to important electrochemical reactions related to energy, including reaction mechanism research, material properties prediction and design of advanced functional materials. To date, more than 120 SCI papers have been published. Some articles were published in Nat. Catal., Nat. Chem. Proc. Natl. Acad. Sci. USA, J. Am. Chem. Soc., J. Phys. Chem. Lett., et al. . Research group homepage: https://tcheng-suda.github.io.
