Journal Articles
2024
S. Li, Z. Zhang, W. R. Marks, X. Huang, H. Chen, D. C. Stoian, R. Erni, C. A. Triana, G. R. Patzke,
{Co4O4} Cubanes in a conducting polymer matrix as bio-inspired molecular oxygen evolution catalysts,
Nature Communications, 2024, 15, 8432
Y. Zhao, W. Wan, R. Erni, L. Pan, G. R. Patzke,
Operando spectroscopic monitoring of metal chalcogenides for overall water splitting: New views of active species and sites,
Angewandte Chemie International Edition, e202400048
W. Wan, Y. Zhao, J. Meng, C. S. Allen, Y. Zhou, G. R. Patzke,
Tailoring C─ N Containing Compounds into Carbon Nanomaterials with Tunable Morphologies for Electrocatalytic Applications,
Small 20 (7), 2304663
2023
Y. Zhao, D. P. Adiyeri Saseendran, C. A. Triana, G. R. Patzke, (Invited)
Understanding and Optimization of Versatile Molecular and Coordination Polymer-Based 3d Transition Metal Oxygen Evolution Reaction Catalysts,
Electrochemical Society Meeting Abstracts 2023, MA2023-02, 2823-2823
H. Chen, J. Li, L. Meng, S. Bae, R. Erni, D. F. Abbott, S. Li, C. A. Triana, V. Mougel, G. R. Patzke,
Modulating Carrier Kinetics in BiVO4 Photoanodes through Molecular Co4O4 Cubane Layers,
Advanced Functional Materials 2023, 33, 2307862
Y. Zhao, D. P. Adiyeri Saseendran, C. Huang, C. A. Triana, W. R. Marks, H. Chen, H. Zhao, G. R. Patzke,
Oxygen Evolution/Reduction Reaction Catalysts: From In Situ Monitoring and Reaction Mechanisms to Rational Design,
Chemical Reviews 2023, 123, 6257-6358
D. P. A. Saseendran, J. W. A. Fischer, L. Müller, D. F. Abbott, V. Mougel, G. Jeschke, C. A. Triana, G. R. Patzke,
Copper(II) defect-cubane water oxidation electrocatalysts: from molecular tetramers to oxidic nanostructures,
Chemical Communications 2023, 59, 5866-5869
2022
J.M. Naik, B. Bulfin, C.A. Triana, D.C. Stoian, G.R. Patzke,
Cation-Deficient Ce-Substituted Perovskite Oxides with Dual-Redox Active Sites for Thermochemical Applications,
ACS Applied Materials & Interfaces 2023, 15, 806–817
Y. Zhao, W. Wan, N. Dongfang, C.A. Triana, L. Douls, C. Huang, R. Erni, M. Iannuzzi, G.R. Patzke,
Optimized NiFe-Based Coordination Polymer Catalysts: Sulfur-Tuning and Operando Monitoring of Water Oxidation,
ACS Nano 2022, 16, 15318-15327
S.E. Balaghi, A.S. Sologubenko, S. Mehrabani, G.R. Patzke, M.M. Najafpour,
Molecular Mechanism of Copper-based Catalytic Reaction of Water Oxidation. In-situ Electrochemical Liquid Phase Transmission Electron Microscopy Study,
Microscopy and Microanalysis 2022, 28, 138-140
S.E. Balaghi, S. Heidari, M. Benamara, H. Beyzavi, G.R. Patzke,
Fluoride etched Ni-based electrodes as economic oxygen evolution electrocatalysts,
International Journal of Hydrogen Energy 2022, 47, 1613-1623
2021
W. Wan, Y. Zhao, S. Wei, C. A. Triana, J. Li, A. Arcifa, C. S. Allen, R. Cao, G. R. Patzke
Mechanistic insight into the active centers of single/dual-atom Ni/Fe-based oxygen electrocatalysts,
Nature Communications 12 (1), 5589
Single-atom catalysts with maximum metal utilization efficiency show great potential for sustainable catalytic applications and fundamental mechanistic studies. We here provide a convenient molecular tailoring strategy based on graphitic carbon nitride as support for the rational design of single-site and dual-site single-atom catalysts. Catalysts with single Fe sites exhibit impressive oxygen reduction reaction activity with a half-wave potential of 0.89 V vs. RHE. We find that the single Ni sites are favorable to promote the key structural reconstruction into bridging Ni-O-Fe bonds in dual-site NiFe SAC. Meanwhile, the newly formed Ni-O-Fe bonds create spin channels for electron transfer, resulting in a significant improvement of the oxygen evolution reaction activity with an overpotential of 270 mV at 10 mA cm−2. We further reveal that the water oxidation reaction follows a dual-site pathway through the deprotonation of *OH at both Ni and Fe sites, leading to the formation of bridging O2 atop the Ni-O-Fe sites.
L. Reith, C. A. Triana, F. Pazoki, M. Amiri, M. Nyman, G. R. Patzke,
Unraveling nanoscale cobalt oxide catalysts for the oxygen evolution reaction: maximum performance, minimum effort,
Journal of the American Chemical Society 143 (37), 15022-15038
The oxygen evolution reaction (OER) is a key bottleneck step of artificial photosynthesis and an essential topic in renewable energy research. Therefore, stable, efficient, and economical water oxidation catalysts (WOCs) are in high demand and cobalt-based nanomaterials are promising targets. Herein, we tackle two key open questions after decades of research into cobalt-assisted visible-light-driven water oxidation: What makes simple cobalt-based precipitates so highly active—and to what extent do we need Co-WOC design? Hence, we started from Co(NO3)2 to generate a precursor precipitate, which transforms into a highly active WOC during the photocatalytic process with a [Ru(bpy)3]2+/S2O82–/borate buffer standard assay that outperforms state of the art cobalt catalysts. The structural transformations of these nanosized Co catalysts were monitored with a wide range of characterization techniques. The results reveal that the precipitated catalyst does not fully change into an amorphous CoOx material but develops some crystalline features. The transition from the precipitate into a disordered Co3O4 material proceeds within ca. 1 min, followed by further transformation into highly active disordered CoOOH within the first 10 min. Furthermore, under noncatalytic conditions, the precursor directly transforms into CoOOH. Moreover, fast precipitation and isolation afford a highly active precatalyst with an exceptional O2 yield of 91% for water oxidation with the visible-light-driven [Ru(bpy)3]2+/S2O82– assay, which outperforms a wide range of carefully designed Co-containing WOCs. We thus demonstrate that high-performance cobalt-based OER catalysts indeed emerge effortlessly from a self-optimization process favoring the formation of Co(III) centers in all-octahedral environments. This paves the way to new low-maintenance flow chemistry OER processes.
J. Li, H. Chen, C. A. Triana, G. R. Patzke
Hematite photoanodes for water oxidation: electronic transitions, carrier dynamics, and surface energetics,
Angewandte Chemie 133 (34), 18528-18544
Z. Abdi, S. E. Balaghi, A. S. Sologubenko, M. G. Willinger, M. Vandichel, J.-R. Shen,
S. I. Allakhverdiev, G. R. Patzke, M. M. Najafpour
Understanding the Dynamics of Molecular Water Oxidation Catalysts with Liquid-Phase Transmission Electron Microscopy: The Case of Vitamin B12,
ACS Sustainable Chemistry & Engineering 9 (28), 9494-9505
H. Chen, J. Li, W. Yang, S. E. Balaghi, C. A. Triana, C. K. Mavrokefalos, G. R. Patzke
The Role of Surface States on Reduced TiO2@BiVO4 Photoanodes: Enhanced Water Oxidation Performance through Improved Charge Transfer,
ACS Catalysis 11 (13), 7637-7646
W. Wan, Y. Zhao, C. A. Triana, J. Li, G. R. Patzke
Noble-Metal-Free Nanostructured and Graphene Supported Electrocatalysts for Water Splitting,
Electrochemical Society Meeting Abstracts 239, 1223-1223
Clean hydrogen production through water splitting is a direct and promising sustainable energy pathway to access and store non-fossil chemical fuels. Synthetic design strategies to access low cost, robust and high performance noble metal-free electrocatalysts are vital for forthcoming water splitting applications. To accomplish this goal, the nanoscale design of multifunctional catalysts based on cost-effective graphene supports, hollow nano-architectures and well-coordinated hybrid organic-inorganic structures has been attracting increasing research interest because of the flexible tuning options of their electronic states, chemical composition and local coordination environments.
Over the last years, we have been implementing systematic investigations based on synthetic design, spectroscopy approaches and computational modeling toward the understanding of the mechanism of action in a series of novel, robust and efficient bi-functional electrocatalysts.
Recently, we explored synergistic effects of NiFe alloys encapsulated into N-doped carbon nanotubes (N-CNTs) supported on reduced graphene (rGO) nanosheets for overall water splitting.[1] This so-called NiFe-N-CNT-rGO electrocatalyst was synthesized through a direct and flexible strategy using g-C3N4 as a precursor, where thermally reduced NiFe nanoparticles act as surface nucleation sites for C species to assist N-CNT growth through an unconventional reduction-nucleation-growth mechanism. The catalyst has a low overpotential of 270 mV for oxygen evolution reaction (OER), being superior in performance to a wide range of reported noble-metal-free catalysts. As revealed from density functional theory (DFT) calculations, N-doping and charge transfer at the CNT walls tune the free energy in the electronic structure toward adsorption of intermediates, which greatly enhanced catalytic performance. This synthetic strategy not only leads to excellent performance and opens up new avenues for other carbon-supported alloy catalysts, but its scalability and easy applicability also render it quite promising for large-scale water splitting applications.
In parallel, we explored molecular strategies to conjugate single active sites of metal-phthalocyanine molecules MPc (M=Ni, Co, Fe) on GO.[2] We aim for a thorough understanding of the role of the local coordination environment around the single metal site in the synergistic mechanisms and the catalytic performance. With an advanced combination of ADF (annular dark field)-STEM, operando X-ray absorption spectroscopy and DFT calculations, we observed changes in the electronic and local structure environment of MPc-GO under operando electrochemical OER conditions. Single active metal Ni, Co, Fe sites attain high valence states due to chemisorbed OH− species upon catalytic activation, while the local orders suffer from structural distortion. These changes in the electronic and structural properties lead to the formation of HO-M-N4 moieties with high OER reactivity under operando conditions. These results provide new insight into the fundamental understanding of structure-performance relationships for single active site catalysts.
Likewise, we studied hollow transition metal sulfide nanoboxes synthesized through anion exchange processes[3] between S2- and CN- species that lead to the formation of Prussian blue (PB), M-S@PB (M=Co, Fe, Ni) heterostructures. We found that the high performance of those nanostructures arises from in situ formation of active Co-Fe oxide/hydroxide species during OER, attaining a superior performance compared to noble-metal-catalysts such as RuO2, with a low overpotential of 286 mV and high durability over longer operational periods. The flexible tuning options of the electronic, chemical and local-atomic coordination of those nanostructures render them promising hybrid catalysts for dual OER and HER over an extended pH range.
We have further explored new soft templating strategies for the first 1D cobalt coordination polymer electrocatalyst with bio-inspired features, and we applied state-of-the-art analytical techniques and computational modeling to monitor its formation in situ and to unravel its structure.[4] The highly durable 1D-cobalt coordination polymer catalyst implements strategies to transfer key motifs of inorganic materials into a hydrogen-bonded ligand environment, namely the embedment of the essential {H2O-Co2(OH)2-OH2} edge-site motif of cobalt oxide catalysts into a flexible and robust organic matrix. While this unconventional catalyst shows exceptional performance in commercial alkaline electrolyzers and organic transformations, its flexible structure offers new pathways toward the rational design of mixed molecular-solid disordered catalysts.