Monitoring the Hydrothermal Growth of Cobalt Spinel Water Oxidation Catalysts: From Preparative History to Catalytic Activity

Reith, Lukas; Lienau, Karla; Cook, Daniel Sean; Moré, René; Walton, Richard I.; Patzke, Greta R.

doi:10.1002/chem.201801565

Cited by 15 publications

(17 citation statements)

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“…While Antonietti and Driess et al 41 tailored the particle size of cobalt oxides with related synthetic methods and found the efficiency of photo- and electrocatalytic water oxidation of Co 3 O 4 nanoparticles to depend on the available surface area, our previous studies on Co 3 O 4 hydrothermal growth mechanisms indicated that the surface area is not by all means the decisive performance parameter. 13…”

Section: Resultsmentioning

confidence: 99%

“…First, the predictivity of inorganic synthetic protocols is still limited, especially with respect to understanding the precise influence of diverse synthetic methods and conditions on crucial material parameters. 9−13 Consequently, establishing predictive preparation–properties–performance relations for WOCs remains a fundamental challenge. Moreover, recent results indicate that the key parameters required for optimal WOC performance can vary significantly with the applied catalytic test method.…”

Section: Introductionmentioning

confidence: 99%

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Preparative History vs Driving Force in Water Oxidation Catalysis: Parameter Space Studies of Cobalt Spinels

et al. 2019

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The development of efficient, stable, and economic water oxidation catalysts (WOCs) is a forefront topic of sustainable energy research. We newly present a comprehensive three-step approach to systematically investigate challenging relationships among preparative history, properties, and performance in heterogeneous WOCs. To this end, we studied (1) the influence of the preparative method on the material properties and (2) their correlation with the performance as (3) a function of the catalytic test method. Spinel-type Co3O4 was selected as a clear-cut model WOC and synthesized via nine different preparative routes. In search of the key material properties for high catalytic performance, these cobalt oxide samples were characterized with a wide range of analytical methods, including X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, powder X-ray diffraction, Raman spectroscopy, BET surface area analysis, and transmission electron microscopy. Next, the corresponding catalytic water oxidation activities were assessed with the three most widely applied protocols to date, namely, photocatalytic, electrocatalytic, and chemical oxidation. The activity of the Co3O4 samples was found to clearly depend on the applied test method. Increasing surface area and disorder as well as a decrease in oxidation states arising from low synthesis temperatures were identified as key parameters for high chemical oxidation activity. Surprisingly, no obvious property–performance correlations were found for photocatalytic water oxidation. In sharp contrast, all samples showed similar activity in electrochemical water oxidation. The substantial performance differences between the applied protocols demonstrate that control and comprehensive understanding of the preparative history are crucial for establishing reliable structure–performance relationships in WOC design.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Preparative History vs Driving Force in Water Oxidation Catalysis: Parameter Space Studies of Cobalt Spinels

et al. 2019

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“…Our work provided deeper insight into the control parameters of hydrothermal WOC formation processes, through a combination of mechanistic in situ and ex situ analytical methods. This comprehensive study provided guidelines about how the WOC performance of binary oxides can be improved through an empirical understanding of their growth mechanisms [58].…”

Section: Spinelsmentioning

confidence: 99%

Water Oxidation Catalysts: The Quest for New Oxide-Based Materials

Mavrokefalos

Patzke

2019

Inorganics

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The expected shortage of fossil fuels as well as the accompanying climate change are among the major challenges of the 21st century. A global shift to a sustainable energy landscape is, therefore, of utmost importance. Over the past few years, solar technologies have entered the energy market and have paved the way to replace fossil-based energy sources, in the long term. In particular, electrochemical solar-to-hydrogen technologies have attracted a lot of interest—not only in academia, but also in industry. Solar water splitting (artificial photosynthesis) is one of the most active areas in contemporary materials and catalysis research. The development of low-cost, efficient, and stable water oxidation catalysts (WOCs) remains crucial for artificial photosynthesis applications, because WOCs still represent a major economical and efficient bottleneck. In the following, we summarize recent advances in water oxidation catalysts development, with selected examples from 2016 onwards. This condensed survey demonstrates that the ongoing quest for new materials and informed catalyst design is a dynamic and rapidly developing research area.

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“…In the case of Co 3 O 4 we recently demonstrated that the growth mechanism can play a key role in the resulting water oxidation activity (Reith et al, 2018). Therefore, we here started from a well-defined microwave protocol for microwave-assisted spinel-type Co 3 O 4 and systematically studied the influence of the synthetic parameters on the properties and catalytic performance of the emerging materials to demonstrate the importance of these parameters in microwave-hydrothermal WOC synthesis (Conrad et al, 2010(Conrad et al, , 2012(Conrad et al, , 2013.…”

Section: Introductionmentioning

confidence: 99%

Microwave-Hydrothermal Tuning of Spinel-Type Co3O4 Water Oxidation Catalysts

et al. 2020

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Water oxidation is the bottleneck reaction for overall water splitting as a direct and promising strategy toward clean fuels. However, the development of robust and affordable heterogeneous water oxidation catalysts remains challenging, especially with respect to the wide parameter space of synthesis and resulting material properties. Oxide catalysts performance in particular has been shown to depend on both synthetic routes and applied catalytic test methods. We here focus on spinel-type Co 3 O 4 as a representative case for an in-depth study of the influence of rather subtle synthetic parameter variations on the catalytic performance. To this end, a series of Co 3 O 4 samples was prepared via time-saving and tunable microwave-hydrothermal synthesis, while systematically varying a single parameter at a time. The resulting spinel-type catalysts were characterized with respect to key materials properties, including crystallinity, oxidation state and surface area using a wide range of analytical methods, such as PXRD, Raman/IR, XAS and XPS spectroscopy. Their water oxidation activity in electrocatalytic and chemical oxidation setups was then compared and correlated with the obtained catalyst properties. Both water oxidation methods displayed related trends concerning favorable synthetic parameters, namely higher activity for lower synthesis temperatures, lower precursor concentrations, addition of hydrogen peroxide and shorter ramping and reaction times, respectively. In addition to the surface area, structural features such as disorder were found to be influential for the water oxidation activity. The results prove that synthetic parameter screening is essential for optimal catalytic performance, given the complexity of the underlying performance-properties relationships.

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Monitoring the Hydrothermal Growth of Cobalt Spinel Water Oxidation Catalysts: From Preparative History to Catalytic Activity

Cited by 15 publications

References 113 publications

Preparative History vs Driving Force in Water Oxidation Catalysis: Parameter Space Studies of Cobalt Spinels

Preparative History vs Driving Force in Water Oxidation Catalysis: Parameter Space Studies of Cobalt Spinels

Water Oxidation Catalysts: The Quest for New Oxide-Based Materials

Microwave-Hydrothermal Tuning of Spinel-Type Co3O4 Water Oxidation Catalysts

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