Csaba Janáky

Csaba Janáky
University of Szeged · Department of Physical Chemistry and Materials Science

PhD

About

138
Publications
20,194
Reads
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3,202
Citations
Additional affiliations
July 2014 - present
University of Szeged
Position
  • Principal Investigator
July 2013 - present
University of Szeged
Position
  • Professor (Assistant)
July 2011 - June 2013
University of Texas at Arlington
Position
  • Marie Curie Fellowship

Publications

Publications (138)
Chapter
Space chemistry is an emerging field, i.e., performing chemistry in space as distinguished from astrochemistry or planetary chemistry. First, our chapter discusses the unique properties (microgravity, low temperature, cosmic ray) of space, pointing out the extraordinary chemistry opportunities. Furthermore, the radical expansion of space industry i...
Article
Achieving high-efficiency photocatalytic conversion of CO2 into value-added chemicals remains a challenge. This study synthesizes In-doped TiO2 and g-C3N4 composites (In-TiO2/g-C3N4) via a facile and reliable method. The as-synthesized In-TiO2/g-C3N4 produces CO, CH4, and C2H4 under UV, and CO and CH4 under visible light from gaseous CO2 and H2O va...
Article
Photo‐electrochemical production of solar fuels from carbon dioxide, water, and sunlight is an appealing approach. Nevertheless, it remains challenging to scale despite encouraging demonstrations at low power input. Higher current densities require notable voltage input as ohmic losses and activation overpotentials become more significant, resultin...
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We demonstrate the dynamic operation of CO2 electrolyzer cells, with a power input mimicking the output of a solar photovoltaic power plant. The zero-gap design ensured efficient intermittent operation for a week, while avoiding significant performance loss.
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The field of electrochemical carbon dioxide reduction has developed rapidly during recent years. At the same time, the role of the anodic half-reaction has received considerably less attention. In this Perspective, we scrutinize the reports on the best-performing CO2 electrolyzer cells from the past 5 years, to shed light on the role of the anodic...
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Lead halide perovskites (LHPs) have emerged as perspective materials for light harvesting, due to their tunable band gap and optoelectronic properties. Photocatalytic and photoelectrochemical (PEC) studies, employing LHP/liquid junctions, are evolving, where sacrificial reagents are often used. In this study, we found that a frequently applied elec...
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A major goal within the CO2 electrolysis community is to replace the generally used Ir anode catalyst with a more abundant material, which is stable and active for water oxidation under process conditions. Ni is widely applied in alkaline water electrolysis, and it has been considered as a potential anode catalyst in CO2 electrolysis. Here we compa...
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The recent coronavirus pandemic pointed out the vulnerability of humanity to new emerging infectious diseases. Experts warn that future pandemics may emerge more frequently with greater devastating effects on population health and the world economy. Although viruses are unable to propagate on lifeless surfaces, they can retain their infectivity and...
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Titanium dioxide (TiO2) is often employed as a light absorber, electron-transporting material and catalyst in different energy and environmental applications. Heat treatment in a hydrogen atmosphere generates black TiO2 (b-TiO2), allowing better absorption of visible light, which placed this material in the forefront of research. At the same time,...
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Continuous-flow electrolysers allow CO2 reduction at industrially relevant rates, but long-term operation is still challenging. One reason for this is the formation of precipitates in the porous cathode from the alkaline electrolyte and the CO2 feed. Here we show that while precipitate formation is detrimental for the long-term stability, the prese...
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The exfoliation of layered materials into two-dimensional (2D) semiconductors creates new structural domains, for example, basal planes, defect-rich in-planes, and edge sites. These surface species affect the photoelectrochemical (PEC) performance, which in turn determines their applicability in solar energy conversion technologies. In this study,...
Article
Studying the effect of nanoscale morphology on the photoelectrochemical performance of semiconductor electrodes has been in the forefront of research for over a decade, there are still major inconsistencies and controversies in the literature. Here we aimed to resolve some of these issues, by the controlled preparation of TiO2 photoelectrodes from...
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Metal–halide perovskites transformed optoelectronics research and development during the past decade. They have also gained a foothold in photocatalytic and photoelectrochemical processes recently, but their sensitivity to the most commonly applied solvents and electrolytes together with their susceptibility to photocorrosion hinders such applicati...
Article
A new anion exchange membrane (PiperION) in conjunction with a tailored zero-gap electrolyzer cell allows unprecedented partial current densities.
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Solar light–driven photoelectrochemical conversion of nitrate ions to nitrite is achieved on copper‐lead iodide nanocomposite electrodes. By optimizing the composition, 1.2 ± 0.05 mA cm⁻² photocurrent density is obtained under concentrated solar irradiation. The reduction products are NO2⁻ and N2, at 0.61 V reversible hydrogen electrode (RHE), whic...
Article
Interest in silver-based semiconductors dates to the early years of analog photography. On the other hand, the recent discovery of new silver oxide-based ternary semiconductors has caused a resurgence of interest in these compounds for new technologies. In this vein, the present study provides a counter example to the two perennial issues confronti...
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In this study, the photoelectrochemical behavior of electrodeposited FeNiOOH/Fe2O3/graphene nanohybrid electrodes is investigated, which has precisely controlled structure and composition. The photoelectrode assembly is designed in a bioinspired manner where each component has its own function: Fe2O3 is responsible for the absorption of light, the...
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Water oxidation (i.e., oxygen evolution) reaction is the most often used, green anodic pair of carbon dioxide (CO2) electroreduction, mimicking the natural photosynthetic process. At the same time, it requires high energy input, and generates a product of little commercial value (i.e., oxygen). Finding appropriate alternative anode processes to be...
Article
Visible light irradiation of the mixed halide perovskite film in contact with a solvent (dichloromethane, DCM) in which the film otherwise is stable, leads to selective expulsion of iodide (I) from the film with concurrent shift in the band edge to lower wavelengths. We have now employed mixed halide perovskites to uncover the influence of A-site c...
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The electrochemical conversion of carbon dioxide (CO2) to high-value chemicals is an attractive approach to create an artificial carbon cycle. Tuning the activity and product selectivity while maintaining long-term stability, however, remains a significant challenge. Here, we study a series of Au–Pb bimetallic electrocatalysts with different Au/Pb...
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According to the currently accepted structure-property relationships, aceno-pentalenes with angular shape (fused to the 1,2-bond of the acene) exhibit higher antiaromaticity than those with linear shape (fused to the 2,3-bond of the acene). To explore and expand the current view, we designed and synthesized molecules where two isomeric, yet, differ...
Preprint
According to the currently accepted structure-property relationships, aceno-pentalenes with angular shape (fused to the 1,2-bond of the acene) exhibit higher antiaromaticity than those with linear shape (fused to the 2,3-bond of the acene). To explore and expand the current view, we designed and synthesized molecules where two isomeric, yet, differ...
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Full-text available
Electrochemical reduction of CO2 is a value-added approach to both decrease the atmospheric emission of carbon-dioxide and to form valuable chemicals. We present a zero gap electrolyzer cell, which continuously converts gas phase CO2 to products without using any liquid catholyte. This is the first report of a multi-layer CO2 electrolyzer stack for...
Article
Halide ion mobility in metal halide perovskites remains an intriguing phenomenon, influencing their optical and photovoltaic properties. Selective injection of holes through electrochemical anodic bias has allowed us to probe the effect of hole trapping at iodide (0.9 V) and bromide (1.15 V) in mixed halide perovskite (CH3NH3PbBr1.5I1.5) films. Upo...
Article
The electrocatalytic reduction of carbon dioxide (CO 2 )on Au–Ag bimetallic alloy nanoparticles was scrutinized. This system provides a good model to investigate the correlation between the electrocatalytic activity and the composition of the nanoparticles. The CO Faradaic efficiency (and thus the forming CO:H 2 ratio)was changed linearly by contro...
Article
The morphology of electrode materials is often overlooked when comparing different carbon-based electrocatalysts for carbon dioxide reduction. To investigate the role of morphological attributes, we studied polymer-derived, interconnected, N-doped carbon structures with uniformly sized meso or macropores, differing only in the pore size. We found t...
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This study focuses on a solid solution series, Ca(La 1-x Ce x ) 2 S 4 (0 ≤ x ≤ 1), where the f electron density is absent in CaLa 2 S 4 and is progressively increased until it is maximized in CaCe 2 S 4 . Correspondingly, these samples, synthesized by a sealed ampule method, showed progressive variations in color ranging from gray for CaLa 2 S 4 to...
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Solution combustion synthesis (SCS) is shown to be versatile for the rapid-one-pot synthesis of three compounds and four polymorphs in the Cu-V-O ternary family: α-CuV2O6, α- and β-Cu2V2O7, and γ-Cu3V2O8. These compounds feature copper: vanadium stoichiometric ratios ranging from 1:1 to 3:1; their structural, electronic, optoelectronic, and photoel...
Article
Owing to its high hole conductivity and ease of preparation, CuI is among the inorganic hole transporting materials that were introduced early on in metal halide perovskite solar cells, but its full potential as a semiconductor material is still to be realized. We have now performed ultrafast spectroelectrochemical experiments on ITO/CuI electrodes...
Article
Detailed mechanistic understanding of the optoelectronic features is a key factor in designing efficient and stable photoelectrodes. In this letter, in situ spectroelectrochemical methods were employed to scrutinize the effect of trap states on the optical and electronic properties of CuI photoelectrodes, and to assess their stability against (phot...
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The ongoing search for new photoelectrode materials generated interest toward semiconductors containing multiple anions. In this work, three different antimony oxide iodides (Sb 3 O 4 I, Sb 8 O 11 I 2 , and Sb 5 O 7 I) were synthesized by anhydrous synthesis. Scanning electron microscopy revealed mainly needle-shaped particles for Sb 3 O 4 I, elong...
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Nickel oxide (NiO) is often used as a hole-transporter material in both photovoltaic and photoelectrochemical solar cells. As a result of the reversible nickel(II)/(III) transformation, it is also electrochromic. These potential-dependent optoelectronic properties of this intriguing material, however, are yet to be fully understood. In this article...
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Bimetallic electrocatalysts offer great flexibility to tailor the activity and selectivity in electrochemical carbon dioxide (CO2) reduction. Here, we report on the electrocatalytic behavior of Au–Sn bimetallic nanoparticles with different intermetallic phases towards CO2 electroreduction. Two high-value products formed with reasonable current dens...
Article
This is a perspective of the role that combustion synthesis, specifically solution combustion synthesis, has played in the development of ternary and quaternary metal oxide semiconductors, and materials derived from these compounds such as composites, solid solutions, and doped samples. The attributes of materials, collectively termed ‘complex oxid...
Article
Electrochemistry, as an analytical tool is gaining its foothold in the characterization of organic metal lead halide per-ovskites, however electrosynthetic applications are yet to be explored fully. Electrochemical deposition of hole-transport layers with desired properties could be an attractive tool to assemble complex solar cell architectures. W...
Article
Given that CO 2 is a greenhouse gas, using the energy of sunlight to convert CO 2 to transportation fuels (such as methanol or methane) represents a value-added approach to the simultaneous generation of alternative fuels and environmental remediation of carbon emissions. Electrochemistry and photoelectrochemistry have been proven to be a useful av...
Article
In this study, we investigated the photoelectrochemical behavior of poly(3,4-ethylenedioxythiophene) (PEDOT)/carbon nanotube (CNT) and PEDOT/graphene nanocomposite photoelectrodes for the first time. Electrodeposition allowed to control both the composition and the morphology (as demonstrated by both transmission and scanning electron microscopy im...
Article
Major efforts are devoted to find efficient and selective electrocatalysts for solar fuel generation, thus enabling accelerated development of such technologies. A series of electrocatalysts from the metal–nitrogen–carbon (M–N–C) family was synthesized by a sacrificial support method (SSM). The salts of Cu, Mo, Pr, and Ce were employed as metal-pre...
Article
Solar fuel generation is a promising avenue to mitigate the harmful effects of the increasing carbon dioxide concentration in the atmosphere. Both photoelectrochemical water splitting and carbon dioxide reduction are viable pathways to utilize solar irradiation, however, there is a strong need for novel photoelectrode materials with enhanced proper...
Article
Isotopic labeling experiments were performed to better understand the electrochemical reduction of carbon dioxide on nitrogen-doped porous carbon electrodes. By using non-equilibrated solutions of the selectively labeled the initial carbon sources (i.e., 13CO2 and H13CO3-), bicarbonate anion was identified as the predominant source of the carbon mo...
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With the rapid development of renewable energy technologies there is an urgent need to find synthesis routes that address the needs of materials in a reproducible and affordable way. In this study, we present a one-step electrochemical method for the deposition of nanocrystalline titanium dioxide films on different carbon substrates. By optimizing...
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This review article addresses areas where solid-state chemistry concepts can contribute to the on-going search for a "magic bullet" inorganic semiconductor that can efficiently split water or reduce CO2. First, a methodology to visualize complex ternary oxide combinations is outlined using 31 examples based on copper in both +1 and +2 oxidation sta...
Chapter
This chapter summarizes the various strategies for the controlled synthesis of conducting polymer/inorganic nanostructure interfaces. We aimed to give a brief overview on the wealth of possibilities, also highlighting the particular importance of each method. The presented approaches span through chemical, electrochemical, and photo-polymerization...
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In this paper, we present the first report when an organic conducting polymer film, alone exhibits both superhydrophobicity and visible light photoactivity. The microstructure of poly(3-hexylthiophene) was optimized using controlled...
Article
The unique optoelectronic properties of lead halide perovskites have triggered a new wave of excitement in materials chemistry during the past five years. Electrochemistry, spectroelectrochemistry, and photoelectrochemistry could be viable tools both for analyzing the optoelectronic features of these materials and to assemble their hybrid architect...
Article
The charging of mesoscopic TiO2 layer in a metal halide perovskite solar cell can influence the overall power conversion efficiency. By employing CsPbBr3 films deposited on a mesoscopic TiO2 film, we have succeeded in probing the influence of electrochemical bias on the charge carrier recombination process. The transient absorption spectroscopy exp...
Article
The growing amount of carbon dioxide (CO2) emission in parallel with the increasing greenhouse effect put the utilization of carbon dioxide in the focus of scientific interest in the past decade. Photoelectrochemical (PEC) conversion of CO2 to useful products is one of the promising possibilities towards reaching this goal. In this paper, we report...
Article
In the search for stable, visible light active photoelectrodes, hydrothermally synthesized tungsten oxide nanowires were modified via nitrogen incorporation into their structure. To this end, nanowires were heat-treated in ammonia/nitrogen atmosphere at different temperatures. This procedure caused transitions in their structure that were investiga...
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Solar fuel generation through electrochemical CO2 conversion offers an attractive avenue to store the energy of sunlight in the form of chemical bonds, with the simultaneous remediation of a greenhouse gas. While impressive progress has been achieved in developing novel nanostructured catalysts and understanding the mechanistic details of this proc...