Origin of enhanced water oxidation activity in an iridium single atom anchored on NiFe oxyhydroxide catalyst

The efficiency of the synthesis of renewable fuels and feedstocks from electrical sources is limited at present by the sluggish water oxidation reaction. Single atom catalysts (SACs) with a controllable coordination environment and exceptional atom utilization efficiency open new paradigms towards designing high performance water oxidation catalysts. Here, using operando X-ray absorption spectroscopy measurements with calculations of spectra and electrochemical activity, we demonstrate that the origin of water oxidation activity of IrNiFe SACs is the presence of highly oxidized Ir single atom (Ir5.3+) in the NiFe oxyhydroxide under operating conditions. We show that the optimal water oxidation catalyst could be achieved by systematically increasing the oxidation state and modulating the coordination environments of the Ir active sites anchored atop the NiFe oxyhydroxide layers. Based on the proposed mechanism, we have successfully anchored Ir single-atom sites on NiFe oxyhydroxides (Ir0.1/Ni9Fe SAC) via a unique in situ cryogenic photochemical reduction (in situ Cryo-PCR) method which delivers an overpotential of 183 millivolts at 10 milliamperes per square centimeter and retains its performance following 20 hours of operation in 1 M KOH electrolyte, outperforming the reported catalysts and the commercial IrO2 catalysts. These findings open the avenue towards atomic-level understanding of oxygen evolution of catalytic centers under in operando condition.

Download Full-text

Origin of Enhanced Water Oxidation Activity in an Iridium Single Atom Catalyst

10.26434/chemrxiv.13708570.v1 ◽

2021 ◽

Author(s):

Xueli Zheng ◽

Jing Tang ◽

Alessandro Gallo ◽

Jose Antonio Garrido Torres ◽

Xiaoyun Yu ◽

...

Keyword(s):

Water Oxidation ◽

Active Sites ◽

High Performance ◽

Operating Conditions ◽

Utilization Efficiency ◽

Oxidation Catalyst ◽

Single Atom ◽

Photochemical Reduction ◽

Oxidation Activity

The efficiency of the synthesis of renewable fuels and feedstocks from electrical sources is limited at present by the sluggish water oxidation reaction. Single atom catalysts (SACs) with a controllable coordination environment and exceptional atom utilization efficiency open new paradigms towards designing high performance water oxidation catalysts. Here, using operando X-ray absorption spectroscopy measurements with calculations of spectra and electrochemical activity, we demonstrate that the origin of water oxidation activity of IrNiFe SACs is the presence of highly oxidized Ir single atom (Ir5.3+) in the NiFe oxyhydroxide under operating conditions. We show that the optimal water oxidation catalyst could be achieved by systematically increasing the oxidation state and modulating the coordination environments of the Ir active sites anchored atop the NiFe oxyhydroxide layers. Based on the proposed mechanism, we have successfully anchored Ir single-atom sites on NiFe oxyhydroxides (Ir0.1/Ni9Fe SAC) via a unique in situ cryogenic photochemical reduction (in situ Cryo-PCR) method which delivers an overpotential of 183 millivolts at 10 milliamperes per square centimeter and retains its performance following 20 hours of operation in 1 M KOH electrolyte, outperforming the reported catalysts and the commercial IrO2 catalysts. These findings open the avenue towards atomic-level understanding of oxygen evolution of catalytic centers under in operando condition.

Download Full-text

An oxidized magnetic Au single atom on doped TiO2(110) becomes a high performance CO oxidation catalyst due to the charge effect

Journal of Materials Chemistry A ◽

10.1039/c7ta05483a ◽

2017 ◽

Vol 5 (36) ◽

pp. 19316-19322 ◽

Cited By ~ 24

Author(s):

J. L. Shi ◽

X. J. Zhao ◽

L. Y. Zhang ◽

X. L. Xue ◽

Z. X. Guo ◽

...

Keyword(s):

Gold Nanoparticles ◽

Co Oxidation ◽

High Performance ◽

Important Application ◽

Oxidation Catalyst ◽

Single Atom ◽

Charge Effect ◽

Extensive Investigation ◽

Doped Tio2

Catalysis using gold nanoparticles supported on oxides has been under extensive investigation for many important application processes.

Download Full-text

Coordination modulation of iridium single-atom catalyst maximizing water oxidation activity

Nature Communications ◽

10.1038/s41467-021-27664-z ◽

2022 ◽

Vol 13 (1) ◽

Author(s):

Zhanwu Lei ◽

Wenbin Cai ◽

Yifei Rao ◽

Kuan Wang ◽

Yuyuan Jiang ◽

...

Keyword(s):

High Activity ◽

Current Density ◽

Water Oxidation ◽

Distribution Density ◽

High Surface ◽

Single Atom ◽

Surface Distribution ◽

Oxidation Activity ◽

Nanosheet Arrays ◽

A Current

AbstractSingle-atom catalysts (SACs) have attracted tremendous research interests in various energy-related fields because of their high activity, selectivity and 100% atom utilization. However, it is still a challenge to enhance the intrinsic and specific activity of SACs. Herein, we present an approach to fabricate a high surface distribution density of iridium (Ir) SAC on nickel-iron sulfide nanosheet arrays substrate (Ir1/NFS), which delivers a high water oxidation activity. The Ir1/NFS catalyst offers a low overpotential of ~170 mV at a current density of 10 mA cm−2 and a high turnover frequency of 9.85 s−1 at an overpotential of 300 mV in 1.0 M KOH solution. At the same time, the Ir1/NFS catalyst exhibits a high stability performance, reaching a lifespan up to 350 hours at a current density of 100 mA cm−2. First-principles calculations reveal that the electronic structures of Ir atoms are significantly regulated by the sulfide substrate, endowing an energetically favorable reaction pathway. This work represents a promising strategy to fabricate high surface distribution density single-atom catalysts with high activity and durability for electrochemical water splitting.

Download Full-text

In Situ EPR Characterization of a Cobalt Oxide Water Oxidation Catalyst at Neutral pH

Catalysts ◽

10.3390/catal9110926 ◽

2019 ◽

Vol 9 (11) ◽

pp. 926 ◽

Cited By ~ 4

Author(s):

Yury Kutin ◽

Nicholas Cox ◽

Wolfgang Lubitz ◽

Alexander Schnegg ◽

Olaf Rüdiger

Keyword(s):

Cobalt Oxide ◽

Water Oxidation ◽

Large Scale ◽

Low Cost ◽

Operating Conditions ◽

Oxidation Catalyst ◽

O2 Evolution ◽

Ligand Field ◽

Neutral Ph

Here we report an in situ electron paramagnetic resonance (EPR) study of a low-cost, high-stability cobalt oxide electrodeposited material (Co-Pi) that oxidizes water at neutral pH and low over-potential, representing a promising system for future large-scale water splitting applications. Using CW X-band EPR we can follow the film formation from a Co(NO3)2 solution in phosphate buffer and quantify Co uptake into the catalytic film. As deposited, the film shows predominantly a Co(II) EPR signal, which converts into a Co(IV) signal as the electrode potential is increased. A purpose-built spectroelectrochemical cell allowed us to quantify the extent of Co(II) to Co(IV) conversion as a function of potential bias under operating conditions. Consistent with its role as an intermediate, Co(IV) is formed at potentials commensurate with electrocatalytic O2 evolution (+1.2 V, vs. SHE). The EPR resonance position of the Co(IV) species shifts to higher fields as the potential is increased above 1.2 V. Such a shift of the Co(IV) signal may be assigned to changes in the local Co structure, displaying a more distorted ligand field or more ligand radical character, suggesting it is this subset of sites that represents the catalytically ‘active’ component. The described spectroelectrochemical approach provides new information on catalyst function and reaction pathways of water oxidation.

Download Full-text

Platinum–copper single atom alloy catalysts with high performance towards glycerol hydrogenolysis

Nature Communications ◽

10.1038/s41467-019-13685-2 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 33

Author(s):

Xi Zhang ◽

Guoqing Cui ◽

Haisong Feng ◽

Lifang Chen ◽

Hui Wang ◽

...

Keyword(s):

Active Sites ◽

High Performance ◽

Reaction Pathway ◽

Theoretical Calculations ◽

Experimental Studies ◽

Value Added ◽

Catalytic Performance ◽

Single Atom ◽

Glycerol Hydrogenolysis ◽

Single Atom Alloy

AbstractSelective hydrogenolysis of biomass-derived glycerol to propanediol is an important reaction to produce high value-added chemicals but remains a big challenge. Herein we report a PtCu single atom alloy (SAA) catalyst with single Pt atom dispersed on Cu nanoclusters, which exhibits dramatically boosted catalytic performance (yield: 98.8%) towards glycerol hydrogenolysis to 1,2-propanediol. Remarkably, the turnover frequency reaches up to 2.6 × 103 molglycerol·molPtCu–SAA−1·h−1, which is to our knowledge the largest value among reported heterogeneous metal catalysts. Both in situ experimental studies and theoretical calculations verify interface sites of PtCu–SAA serve as intrinsic active sites, in which the single Pt atom facilitates the breakage of central C–H bond whilst the terminal C–O bond undergoes dissociation adsorption on adjacent Cu atom. This interfacial synergistic catalysis based on PtCu–SAA changes the reaction pathway with a decreased activation energy, which can be extended to other noble metal alloy systems.

Download Full-text

Anion-exchange synthesis of a nanoporous crystalline CoB2O4 nanowire array for high-performance water oxidation electrocatalysis in borate solution

Nanoscale ◽

10.1039/c7nr04344a ◽

2017 ◽

Vol 9 (34) ◽

pp. 12343-12347 ◽

Cited By ~ 16

Author(s):

Guilei Zhu ◽

Lin Yang ◽

Rong Zhang ◽

Fengli Qu ◽

Zhiang Liu ◽

...

Keyword(s):

Anion Exchange ◽

Water Oxidation ◽

High Performance ◽

Nanowire Array ◽

Oxidation Catalyst ◽

Borate Solution ◽

Catalyst Electrode

A nanoporous crystalline CoB2O4 nanowire array (CoB2O4/TM) behaves as a superior water oxidation catalyst electrode, requiring an overpotential of 446 mV to deliver 10 mA cm−2 in 0.1 M K-Bi (pH = 9.2).

Download Full-text

Activation of surface lattice oxygen in single-atom Pt/CeO2 for low-temperature CO oxidation

Science ◽

10.1126/science.aao2109 ◽

2017 ◽

Vol 358 (6369) ◽

pp. 1419-1423 ◽

Cited By ~ 458

Author(s):

Lei Nie ◽

Donghai Mei ◽

Haifeng Xiong ◽

Bo Peng ◽

Zhibo Ren ◽

...

Keyword(s):

Low Temperature ◽

Co Oxidation ◽

Active Sites ◽

Fuel Efficiency ◽

Steam Treatment ◽

Single Atom ◽

Oxidation Activity ◽

Formidable Challenge ◽

Low Temperature Co Oxidation ◽

Exhaust Treatment

To improve fuel efficiency, advanced combustion engines are being designed to minimize the amount of heat wasted in the exhaust. Hence, future generations of catalysts must perform at temperatures that are 100°C lower than current exhaust-treatment catalysts. Achieving low-temperature activity, while surviving the harsh conditions encountered at high engine loads, remains a formidable challenge. In this study, we demonstrate how atomically dispersed ionic platinum (Pt2+) on ceria (CeO2), which is already thermally stable, can be activated via steam treatment (at 750°C) to simultaneously achieve the goals of low-temperature carbon monoxide (CO) oxidation activity while providing outstanding hydrothermal stability. A new type of active site is created on CeO2 in the vicinity of Pt2+, which provides the improved reactivity. These active sites are stable up to 800°C in oxidizing environments.

Download Full-text

CoOx nanoparticle anchored on sulfonated-graphite as efficient water oxidation catalyst

Chemical Science ◽

10.1039/c7sc01756a ◽

2017 ◽

Vol 8 (9) ◽

pp. 6111-6116 ◽

Cited By ~ 41

Author(s):

Jingqi Guan ◽

Chunmei Ding ◽

Ruotian Chen ◽

Baokun Huang ◽

Xianwen Zhang ◽

...

Keyword(s):

Water Oxidation ◽

Oxidation Catalyst ◽

Oxidation Activity ◽

Solar Water ◽

Highly Efficient ◽

Solar Water Oxidation

Ultrasmall CoOx nanoparticles on sulfonated graphite exhibit highly efficient water oxidation activity and can be used for electrochemical and solar water oxidation.

Download Full-text