scholarly journals Tuning the Electronic Structure of CoO Nanowire Arrays by N-Doping for Efficient Hydrogen Evolution in Alkaline Solutions

Catalysts ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1237
Author(s):  
Maoqi Cao ◽  
Xiaofeng Li ◽  
Dingding Xiang ◽  
Dawang Wu ◽  
Sailan Sun ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Hydrogen Evolution ◽  
Current Density ◽  
Nanowire Arrays ◽  
Alkaline Media ◽  
Water Dissociation ◽  
Alkaline Condition ◽  
Alkaline Solutions ◽  
X Ray ◽  
Production Of Hydrogen

Electrochemical hydrogen evolution reactions (HER) have drawn tremendous interest for the scalable and sustainable conversion of renewable electricity to clear hydrogen fuel. However, the sluggish kinetics of the water dissociation step severely restricts the high production of hydrogen in alkaline media. Tuning the electronic structure by doping is an effective method to boost water dissociation in alkaline solutions. In this study, N-doped CoO nanowire arrays (N-CoO) were designed and prepared using a simple method. X-ray diffraction (XRD), element mappings and X-ray photoelectron spectroscopy (XPS) demonstrated that N was successfully incorporated into the lattice of CoO. The XPS of Co 2p and O 1s suggested that the electronic structure of CoO was obviously modulated after the incorporation of N, which improved the adsorption and activation of water molecules. The energy barriers obtained from the Arrhenius relationship of the current density at different temperatures indicated that the N-CoO nanowire arrays accelerated the water dissociation in the HER process. As a result, the N-CoO nanowire arrays showed an excellent performance of HER in alkaline condition. At a current density of 10 mA cm−1, the N-CoO nanowire arrays needed only a 123 mV potential, which was much lower than that of CoO (285 mV). This simple design strategy provides some new inspiration to promote water dissociation for HER in alkaline solutions at the atomic level.

scholarly journals Charge localized atomic Moδ+ site boosting hydrogen evolution in alkaline solution

2020 ◽  
Author(s):  
Maoqi Cao ◽  
Kang Liu ◽  
Yao Song ◽  
Chao Ma ◽  
Yiyang Lin ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Active Site ◽  
Density Functional ◽  
Alkaline Media ◽  
Water Dissociation ◽  
Single Atom ◽  
Alkaline Solutions ◽  
X Ray ◽  
Tafel Slope ◽  
Charge Localization

Abstract Electrochemical water splitting has drawn tremendous interest for the scalable and sustainable conversion of renewable electricity to clear hydrogen fuel and chemicals. However, the sluggishly kinetics of water dissociation step in alkaline solutions restrict severely the application of hydrogen evolution reaction (HER). Here, we designed and prepared cobalt layers with nitrogen modified atomically dispersed Mo sites (N-Mo/Co SAA) to boost the activity of HER. Density functional theory (DFT) calculations demonstrated that the N can induce the asymmetry charge localization of Moδ+ to facilitate the water dissociation. The energy barriers of water dissociation reduced from 0.48 to 0.35 eV by the charge localized Moδ+ site. High resolution transmission electron microscope (HRTEM) and synchrotron X-ray absorption spectroscopy (XAS) measurements confirmed the structure of N modified atomically dispersed Moδ+. Ambient pressure X-ray photoelectron spectroscopy (AP-XPS) measurements assessed the atomically dispersed Moδ+ site is the active site for water dissociation. Thus, the obtained N-Mo/Co catalyst exhibits record activity with 12 mV overpotential to achieve the current density of 10 mA cm− 2 and Tafel slope of 31 mV dec− 1 in alkaline media, which are superior to 32 mV overpotential for 10 mA cm− 2 and 38 mV dec− 1 Tafel slope on best commercial 20 wt% Pt/C sample in the same condition. This design strategy provided a new pathway to boost the activity of single atom alloy (SAA) by regulating the charge localization of the active site precisely at the atomic-level.

scholarly journals Facile Synthesis of PdCuRu Porous Nanoplates as Highly Efficient Electrocatalysts for Hydrogen Evolution Reaction in Alkaline Medium

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1451
Author(s):  
Changhong Chen ◽  
Ningkang Qian ◽  
Junjie Li ◽  
Xiao Li ◽  
Deren Yang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Alkaline Solution ◽  
Current Density ◽  
Alkaline Media ◽  
Water Dissociation ◽  
Galvanic Replacement ◽  
Facile Synthesis ◽  
Better Than

Ru is a key component of electrocatalysts for hydrogen evolution reaction (HER), especially in alkaline media. However, the catalytic activity and durability of Ru-based HER electrocatalysts are still far from satisfactory. Here we report a solvothermal approach for the synthesis of PdCuRu porous nanoplates with different Ru compositions by using Pd nanoplates as the seeds. The PdCuRu porous nanoplates were formed through underpotential deposition (UPD) of Cu on Pd, followed by alloying Cu with Pd through interdiffusion and galvanic replacement between Cu atoms and Ru precursor simultaneously. When evaluated as HER electrocatalysts, the PdCuRu porous nanoplates exhibited excellent catalytic activity and durability. Of them, the Pd24Cu29Ru47/C achieved the lowest overpotential (40.7 mV) and smallest Tafel slope (37.5 mV dec−1) in an alkaline solution (much better than commercial Pt/C). In addition, the Pd24Cu29Ru47/C only lost 17% of its current density during a stability test for 10 h, while commercial Pt/C had a 59.5% drop under the same conditions. We believe that the electron coupling between three metals, unique porous structure, and strong capability of Ru for water dissociation are responsible for such an enhancement in HER performance.

scholarly journals The Synergistic Effects of Alloying on the Performance and Stability of Co3Mo and Co7Mo6 for the Electrocatalytic Hydrogen Evolution Reaction

Hydrogen ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 11-21
Author(s):  
Youyi Sun ◽  
Alexey Y. Ganin
Keyword(s):  
Hydrogen Evolution ◽  
Synergistic Effects ◽  
Alkaline Media ◽  
Price Of Stability ◽  
X Ray Diffraction ◽  
Free Standing ◽  
X Ray ◽  
Current Decay ◽  
Earth Abundant ◽  
Current Densities

Metal alloys have become a ubiquitous choice as catalysts for electrochemical hydrogen evolution in alkaline media. However, scarce and expensive Pt remains the key electrocatalyst in acidic electrolytes, making the search for earth-abundant and cheaper alternatives important. Herein, we present a facile and efficient synthetic route towards polycrystalline Co3Mo and Co7Mo6 alloys. The single-phased nature of the alloys is confirmed by X-ray diffraction and electron microscopy. When electrochemically tested, they achieve competitively low overpotentials of 115 mV (Co3Mo) and 160 mV (Co7Mo6) at 10 mA cm−2 in 0.5 M H2SO4, and 120 mV (Co3Mo) and 160 mV (Co7Mo6) at 10 mA cm−2 in 1 M KOH. Both alloys outperform Co and Mo metals, which showed significantly higher overpotentials and lower current densities when tested under identical conditions, confirming the synergistic effect of the alloying. However, the low overpotential in Co3Mo comes at the price of stability. It rapidly becomes inactive when tested under applied potential bias. On the other hand, Co7Mo6 retains the current density over time without evidence of current decay. The findings demonstrate that even in free-standing form and without nanostructuring, polycrystalline bimetallic electrocatalysts could challenge the dominance of Pt in acidic media if ways for improving their stability were found.

scholarly journals A Mini Review on Doped Nickel-Based Electrocatalysts for Hydrogen Evolution Reaction

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4651
Author(s):  
Yilin Deng ◽  
Wei Lai ◽  
Bin Xu
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Water Electrolysis ◽  
Energy Resources ◽  
Alkaline Media ◽  
Hydrogen Energy ◽  
Heteroatom Doping ◽  
Highly Active ◽  
Production Of Hydrogen

The energy crisis and environmental pollution have attracted much attention and have promoted researches on clean and sustainable hydrogen energy resources. With the help of highly active and stable transition metal nickel-based catalysts, the production of hydrogen from water electrolysis from electrolyzed water has become an inexpensive and efficient strategy for generating hydrogen energy. In recent years, heteroatom doping has been found to be an effective strategy to improve the electrocatalytic hydrogen evolution reaction (HER) performances of nickel-based catalysts in acidic, neutral, and alkaline media. This review will highlight many recent works of inexpensive and readily available heteroatom-doped nickel-based HER catalysts. The evaluation methods for the performances of HER catalyst will be briefly described, and the role of heteroatom doping and its application in nickel-based catalyst will be summarized. This article will also point out some heteroatom doping strategies, which may provide references and inspire the design of other catalysts with dopants.

Experimental and theoretical investigation on MoS2/MXene heterostructure as an efficient electrocatalyst for hydrogen evolution in both acidic and alkaline media

2020 ◽  
Vol 44 (19) ◽  
pp. 7902-7911
Author(s):  
Le Hu ◽  
Yuyun Sun ◽  
Shi-Jing Gong ◽  
Hui Zong ◽  
Ke Yu ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Theoretical Investigation ◽  
Alkaline Media ◽  
Alkaline Solutions ◽  
Acidic And Alkaline Media

A composite of MoS2/Nb2CTx with MoS2 nanoflowers grown between Nb2CTx flakes for electrolysis of water in acidic and alkaline solutions.

scholarly journals Boosting alkaline hydrogen evolution: the dominating role of interior modification in surface electrocatalysis

2020 ◽  
Vol 13 (9) ◽  
pp. 3110-3118 ◽  
Author(s):  
Zhao Li ◽  
Wenhan Niu ◽  
Zhenzhong Yang ◽  
Abdelkader Kara ◽  
Qi Wang ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Water Dissociation ◽  
Alkaline Solutions ◽  
Great Promise ◽  
Hydrogen Fuel ◽  
Practical Utilization

The alkaline hydrogen evolution reaction (A-HER) holds great promise for clean hydrogen fuel generation but its practical utilization is severely hindered by the sluggish kinetics for water dissociation in alkaline solutions.

Ni3[Fe(CN)6]2 nanocubes boost the catalytic activity of Pt for electrochemical hydrogen evolution

2018 ◽  
Vol 5 (7) ◽  
pp. 1683-1689 ◽  
Author(s):  
Xiao Zhang ◽  
Pei Liu ◽  
Yanfang Sun ◽  
Tianrong Zhan ◽  
Qingyun Liu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Reaction Kinetics ◽  
Hydrogen Evolution ◽  
Alkaline Media ◽  
Water Dissociation ◽  
Acidic And Alkaline Media ◽  
Ni Species ◽  
Low Pt Loading ◽  
Kinetics Of

Hybrid electrocatalyst of ultrafine Pt particles anchored on a Ni3[Fe(CN)6]2 nanocube with low Pt loading of 4.0% is designed for HERs, and superior catalytic activity is obtained in both acidic and alkaline media because the Ni species remarkably facilitates the reaction kinetics of water dissociation and thus improves HER activity.

MOF-derived hierarchical 3D bi-doped CoP nanoflower eletrocatalyst for hydrogen evolution reaction in both acidic and alkaline media

2020 ◽  
Vol 56 (56) ◽  
pp. 7702-7705 ◽  
Author(s):  
Lei Guo ◽  
Xue Bai ◽  
Hui Xue ◽  
Jing Sun ◽  
Tianshan Song ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Current Density ◽  
Alkaline Media ◽  
Alkaline Electrolyte ◽  
Acidic Electrolyte ◽  
Acidic And Alkaline Media ◽  
A Current

A 3D hierarchical Bi-doped CoP nanoflowers electrocatalyst is developed based on a MOF self-sacrifice strategy. The 3% Bi/CoP catalyst delivers a current density of 10 mA cm−2 at low overpotentials of 122 mV in alkaline electrolyte and 150 mV in acidic electrolyte.

Tungsten-doped Ni–Co phosphides with multiple catalytic sites as efficient electrocatalysts for overall water splitting

2019 ◽  
Vol 7 (28) ◽  
pp. 16859-16866 ◽  
Author(s):  
Shan-Shan Lu ◽  
Li-Ming Zhang ◽  
Yi-Wen Dong ◽  
Jia-Qi Zhang ◽  
Xin-Tong Yan ◽  
...  
Keyword(s):  
Reaction Kinetics ◽  
Hydrogen Evolution ◽  
Water Splitting ◽  
Hydrogen Evolution Reaction ◽  
Alkaline Media ◽  
Water Dissociation ◽  
Overall Water Splitting ◽  
Catalytic Sites ◽  
Additional Water ◽  
Dissociation Step

The design of electrocatalysts including precious and nonprecious metals for the hydrogen evolution reaction (HER) in alkaline media remains challenging due to the sluggish reaction kinetics caused by the additional water dissociation step.

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