Publications by authors named "Eko Budiyanto"

4 Publications

  • Page 1 of 1

Impact of Single-Pulse, Low-Intensity Laser Post-Processing on Structure and Activity of Mesostructured Cobalt Oxide for the Oxygen Evolution Reaction.

ACS Appl Mater Interfaces 2021 Jul 29. Epub 2021 Jul 29.

Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany.

Herein, we report nanosecond, single-pulse laser post-processing (PLPP) in a liquid flat jet with precise control of the applied laser intensity to tune structure, defect sites, and the oxygen evolution reaction (OER) activity of mesostructured CoO. High-resolution X-ray diffraction (XRD), Raman, and X-ray photoelectron spectroscopy (XPS) are consistent with the formation of cobalt vacancies at tetrahedral sites and an increase in the lattice parameter of CoO after the laser treatment. X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) further reveal increased disorder in the structure and a slight decrease in the average oxidation state of the cobalt oxide. Molecular dynamics simulation confirms the surface restructuring upon laser post-treatment on CoO. Importantly, the defect-induced PLPP was shown to lower the charge transfer resistance and boost the oxygen evolution activity of CoO. For the optimized sample, a 2-fold increment of current density at 1.7 V vs RHE is obtained and the overpotential at 10 mA/cm decreases remarkably from 405 to 357 mV compared to pristine CoO. Post-mortem characterization reveals that the material retains its activity, morphology, and phase structure after a prolonged stability test.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsami.1c08034DOI Listing
July 2021

A Highly-Efficient Oxygen Evolution Electrocatalyst Derived from a Metal-Organic Framework and Ketjenblack Carbon Material.

Chempluschem 2021 Jul 1;86(8):1106-1115. Epub 2021 Jul 1.

Institut für Anorganische Chemie und Strukturchemie, Heinrich-, Heine-Universität Düsseldorf Universitätsstraße 1, 40225, Düsseldorf, Germany.

The composite of the metal-organic framework (MOF) Ni(Fe)-MOF-74 and the highly conductive carbon material ketjenblack (KB) could be easily obtained from the in-situ MOF synthesis in a one-step solvothermal reaction. The composite material features a remarkable electrochemical oxygen evolution reaction (OER) performance where the overpotential at 10 mA/cm and the current density at 1.7 V are recorded as 0.274 V and 650 mA/cm , respectively, in 1 mol/L KOH. In particular, the activation of nickel-iron clusters from the MOF under an applied anodic bias steadily boosts the OER performance. Although Ni(Fe)-MOF-74 goes through some structural modification during the electrochemical measurements, the stabilized and optimized composite material shows excellent OER performance. This simple strategy to design highly-efficient electrocatalysts, utilizing readily available precursors and carbon materials, will leverage the use of diverse metal-organic complexes into electrode fabrication with a high energy conversion efficiency.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/cplu.202100278DOI Listing
July 2021

Principles of Water Electrolysis and Recent Progress in Cobalt-, Nickel-, and Iron-Based Oxides for the Oxygen Evolution Reaction.

Angew Chem Int Ed Engl 2021 Jun 17. Epub 2021 Jun 17.

Department of Heterogeneous Catalysis, Max-Planck-Institute für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany.

Water electrolysis that results in green hydrogen is the key process towards a circular economy. The supply of sustainable electricity and availability of oxygen evolution reaction (OER) electrocatalysts are the main bottlenecks of the process for large-scale production of green hydrogen. A broad range of OER electrocatalysts have been explored to decrease the overpotential and boost the kinetics of this sluggish half-reaction. Co-, Ni-, and Fe-based catalysts have been considered to be potential candidates to replace noble metals due to their tunable 3d electron configuration and spin state, versatility in terms of crystal and electronic structures, as well as abundance in nature. This Review provides some basic principles of water electrolysis, key aspects of OER, and significant criteria for the development of the catalysts. It provides also some insights on recent advances of Co-, Ni-, and Fe-based oxides and a brief perspective on green hydrogen production and the challenges of water electrolysis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/anie.202103824DOI Listing
June 2021

Tunable e Orbital Occupancy in Heusler Compounds for Oxygen Evolution Reaction*.

Angew Chem Int Ed Engl 2021 Mar 3;60(11):5800-5805. Epub 2021 Feb 3.

Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany.

Heusler compounds have potential in electrocatalysis because of their mechanical robustness, metallic conductivity, and wide tunability in the electronic structure and element compositions. This study reports the first application of Co YZ-type Heusler compounds as electrocatalysts for the oxygen evolution reaction (OER). A range of Co YZ crystals was synthesized through the arc-melting method and the e orbital filling of Co was precisely regulated by varying Y and Z sites of the compound. A correlation between the e orbital filling of reactive Co sites and OER activity was found for Co MnZ compounds (Z=Ti, Al, V, and Ga), whereby higher catalytic current was achieved for e orbital filling approaching unity. A similar trend of e orbital filling on the reactivity of cobalt sites was also observed for other Heusler compounds (Co VZ, Z=Sn and Ga). This work demonstrates proof of concept in the application of Heusler compounds as a new class of OER electrocatalysts, and the influence of the manipulation of the spin orbitals on their catalytic performance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/anie.202013610DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7986729PMC
March 2021
-->