
Gergely Ferenc SamuUniversity of Szeged · Department of Molecular and Analytical Chemistry
Gergely Ferenc Samu
PhD
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72
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January 2013 - January 2024
Publications
Publications (72)
Photoinduced segregation in mixed halide perovskite has a direct influence on decreasing the solar cell efficiency as segregated I-rich domains serve as charge recombination centers. The changes in the external quantum efficiency mirrors the spectral loss in the absorption, however the timescale of the IPCE recovery in the dark is slower than the a...
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...
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...
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...
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...
Ternary cesium-copper halide pseudo-perovskites are an emerging class of semiconductors in the field of optoelectronics. Similarly, to metal-halide perovskites, by controlling the halide-composition, their emission properties can be fine-tuned. Here...
Electrochemical reduction of carbon monoxide offers a possible route to produce valuable chemicals (such as acetate, ethanol or ethylene) from CO2 in two consecutive electrochemical reactions. Such deeply reduced products are formed via the transfer of 4–6 electrons per CO molecule. Assuming similar-sized CO2 and CO electrolyzers, 2–3-times larger...
Antioxidant nanozymes are powerful tools to combat oxidative stress, which can be further improved by applying nanozyme mixtures of multiple enzymatic function. Here, cocktails of Prussian blue (PB) nanocubes and copper(II) exchanged ZSM-5 zeolites (CuZ) with enhanced reactive oxygen species (ROS) scavenging activity were developed. Surface functio...
Understanding photophysical processes in lead halide perovskites is an important aspect of optimizing the performance of optoelectronic devices. The determination of exact charge carrier extraction rate constants remains elusive, as there is a large and persistent discrepancy in the reported absolute values. In this review, we concentrate on experi...
Photoelectrochemistry holds the promise of directly converting sunlight to valuable chemical products. Photoelectrochemical (PEC) methods, however, lag behind their electrochemical counterparts in terms of current density. In this work, we demonstrate that, by using concentrated sunlight, we can achieve current densities similar to electrochemical...
The kinetics of electron extraction at the electron transfer layer/perovskite interface strongly affects the efficiency of a perovskite solar cell. By combining transient absorption and time-resolved photoluminescence spectroscopy, the electron extraction process between FA0.83Cs0.17Pb(I0.83Br0.17)3 and TiO2 single crystals with different orientati...
As cancer cells exhibit an increased uptake of iron, targeting the interaction with iron has become a straightforward strategy in the fight against cancer. This work comprehensively characterizes the chemical properties of 6-methyl-3-{(2E)-2-[1-(2-pyridinyl)ethylidene]hydrazino}-5H-[1,2,4]triazino[5,6-b]indole (VLX600), a clinically investigated ir...
Photoelectrodes with FTO/Au/Sb2Se3/TiO2/Au architecture were studied in photoelectrochemical CO2 reduction reaction (PEC CO2RR). The preparation is based on a simple spin coating technique, where nanorod-like structures were obtained for Sb2Se3, as confirmed by SEM images. A thin conformal layer of TiO2 was coated on the Sb2Se3 nanorods via ALD, wh...
Biocompatible Cu(II)-doped layered double hydroxide (CMA) nanoparticles were developed to combat reactive oxygen species. The 2-dimensional nanozymes showed both superoxide dismutase and catalase-like activity in chemical assays, while proved as...
2D transition metal dichalcogenides are an attractive family of materials in the field of electronics and optoelectronics. They are excellent candidates for sensitive photodetectors, light harvesting devices (photovoltaics, photocatalysts or photoelectrodes), lasers or non-linear optical devices. All these applications rely on light-matter interact...
Photoelectrodes with architecture FTO/Au/Sb 2 Se 3 /TiO 2 for solar hydrogen evolution reactions (HER) and CO 2 reduction reactions (CO2RR) were studied. The fabrication followed a simple spin-coating technique whereby nanorod-like structures were obtained for the Sb 2 Se 3 as shown in the SEM images. A layer of TiO 2 was deposited via ALD which ac...
Ternary copper halide pseudo‐perovskites are in the forefront of research as potential active materials in light emission applications. The optoelectronic properties of these compounds can be fine‐tuned by the preparation of mixed‐halide compositions. After irradiation, self‐trapped excitonic states are formed in these materials. However, the emiss...
In the current work, we first present a simple synthesis method for the preparation of novel Vitamin-B1-stabilized few-atomic gold nanoclusters with few atomic layers. The formed nanostructure contains ca. eight Au atoms and shows intensive blue emissions at 450 nm. The absolute quantum yield is 3%. The average lifetime is in the nanosecond range a...
While CO can already be produced at industrially relevant current densities via CO2 electrolysis, the selective formation of C2+ products seems challenging. CO electrolysis, in principle, can overcome this barrier, hence forming valuable chemicals from CO2 in two steps. Here we demonstrate that a mass-produced, commercially available polymeric pore...
Here we report a facile sulfation of TiO2 semiconductor photocatalyst by simply grinding and calcination method using elemental sulfur from desulfurisation of petroleum. The successful sulfation of the prepared visible light active was proved by FT‐IR and XPS measurements, as well. The photocatalytic tests revealed that the S‐TiO2‐2 is the most eff...
Alpha‐Particle Detections In article number 2206645, Csaba Janáky, Mátyás Hunyadi, and coworkers demonstrate the spectroscopic detection of charged particles with cesium copper halide thin films. This study shows the first use of inorganic thin‐film scintillators with optical pulse characteristics and light yield competitive with doped single cryst...
Cooperative Bi(III)/Co(II) and Bi(III)/Mn(II) heterogeneous catalysts have been developed enabling efficient oxidative annulations for preparing both cross-coupled imines and benzimidazoles under ambient conditions in an atom-economic and time-efficient manner, involving ambient air as oxidant and without the need of any other additives. This is th...
We measured the exciton dynamics in van der Waals heterojunctions of transition metal dichalcogenides (TMDCs) and organic semiconductors (OSs). TMDCs and OSs are semiconducting materials with rich and highly diverse optical and electronic properties. Their heterostructures, exhibiting van der Waals bonding at their interfaces, can be utilized in th...
Photoelectrochemical (PEC) hydrogen evolution reaction (HER) was studied on exfoliated, pristine and Pt‐decorated tungsten diselenide (p‐WSe2) nanoflake samples, using a previously developed microdroplet PEC microscopy approach. The WSe2 nanoflakes had well‐defined thicknesses as measured by atomic force microscopy, and the Pt nanoparticles (NPs) w...
Herein, the first study on the scintillation properties of CsCu2X3 and Cs3Cu2X5 (where X: Cl⁻, Br⁻, I⁻) is presented, describing their charged particle‐induced luminescence involving electrons, protons, α‐particles, and heavy ions, as well as revealing their capabilities on the timing and spectroscopic evaluation of single‐particle events. The thin...
N-doped carbon (N-C) materials are increasingly popular in different electrochemical and catalytic applications. Due to the structural and stoichiometric diversity of these materials, however, the role of different functional moieties is still controversial. We have synthesized a set of N-C catalysts, with identical morphologies (∼27 nm pore size)....
In this paper, we firstly demonstrate a simple and reproducible synthesis protocol to produce nicotinamide-stabilized gold nanoclusters (NAM-Au NCs) under mild conditions. The dominant role of the pH and the ligand to metal ion molar ratio on the formation of these few atomic fluorescent NCs were proven. The prepared NCs show intensive blue-emissio...
Antioxidant colloids were developed via controlled heteroaggregation of cerium oxide nanoparticles (CeO2 NPs) and sulfate-functionalized polystyrene latex (SL) beads. Positively charged CeO2 NPs were directly immobilized onto SL particles of opposite surface charge via electrostatic attraction (SL/Ce composite), while negatively charged CeO2 NPs we...
With the increasing demand for liquid manipulation and microfluidic techniques, surfaces with external stimuli induced real-time tunable wetting properties are getting into the focus of materials science research. In this study, we present poly(dimethylsiloxane) (PDMS) copolymer-based composite coatings with thermally adjustable wetting and visible...
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...
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...
An efficient self-supported Cu(II)Bi(III) bimetallic catalyst with a layered structure was designed and developed. By careful characterization of the as-prepared material, the host structure was identified to exhibit a Sillen-type bismutite framework, with copper(II) ions being loaded as guests. The heterogeneous catalyst enabled C-N and C-S arylat...
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,...
The preparation of an antioxidant hybrid material by controlled heteroaggregation of manganese oxide nanoparticles (MnO2 NPs) and sulfate-functionalized polystyrene latex (SL) beads was accomplished. Negatively charged MnO2 NPs were prepared by precipitation and initially functionalized with poly(diallyldimethylammonium chloride) (PDADMAC) polyelec...
Visible light irradiation of a mixed halide perovskite (with bromide and iodide in the X-site) in contact with a solvent like dichloromethane (DCM) leads to selective expulsion of iodide from the film. This causes a concurrent blue-shift in band edge. We find that addition of Cs to A-site reduces the mobility of iodide ions under photoirradiation....
The construction of a donor-acceptor Stenhouse adduct molecular layer on a gold surface is presented. To avoid the incompatibility of the thiol surface-binding group with the donor-acceptor polyene structure of the switch, an interfacial reaction approach was followed. Poly(dopamine)-supported gold nanoparticles on quartz slides were chosen as subs...
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...
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...
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...
Prussian blue (PB) nanoparticles of intrinsic peroxidase and superoxide dismutase-like activities were prepared by a co-precipitation method and immobilized on amidine functionalized polystyrene latex (AL) particles. The interaction between the AL and PB particles and the colloidal stability of the resulting AL-PB hybrid composites were assessed at...
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...
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...
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...
Semiconducting materials are essential building blocks of the majority of devices in the 21 st century. The ability of semiconductors to generate charge carriers under band gap irradiation makes them suitable for a myriad of applications (e.g., solar cells, photocatalysts, photodetectors). In recent years the emergence of organic-inorganic lead hal...
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...
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...
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...
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...
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...
The ternary compound, CuBi2O4, a 1:1 stoichiometric derivative of the two component oxides CuO and Bi2O3, has attracted attention from the solar water splitting and photocatalysis communities as a p-type semiconductor responsive to visible light. This study demonstrates that solution combustion synthesis (SCS) can be used to prepare powders not onl...
Photoelectrochemical hydrogen evolution is a promising avenue to store the energy of sunlight in the form of chemical bonds. The recent rapid development of new synthetic approaches enables the nanoscale engineering of semiconductor photoelectrodes, thus tailoring their physico-chemical properties towards efficient H2 formation. In this work we car...
This article focuses on variation in the values for the optical bandgaps (Eg) experimentally reported for fourteen oxide semiconductors that have been studied for solar photoelectrochemical and photocatalytic environmental remediation applications. Both binary and ternary compounds have been included in this study. The variance in the reported valu...
Ternary and quaternary metal oxides form a rapidly emerging class of new functional materials tackling the grand challenge of efficient solar energy harvesting. Currently the main interest is devoted to the characteristics of these materials and little consideration has been given to their preparation. Solution combustion synthesis (SCS) is conside...
In this study, we demonstrate that by directly employing single-walled carbon nanotube arrays (SWCNT-arrays)—grown on conductive substrates—as working electrodes, selective and uniform electrodeposition of a conducting polymer, namely poly(3-hexylthiophene), can be achieved on the surface of the nanotubes. The overall kinetic pattern of the electro...
Co and Rh+Co catalysts supported on Al2O3 and CeO2 were investigated by temperature programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). The CeO2 defects, resulted from the effects of the metals, were further analyzed by Raman spectroscopy and optical absorption. Although the interaction of Co with these two supports is fairly dif...
In the search for highly active and stable photocatalysts, significant efforts are devoted to find both new materials and innovative synthetic methods. In this study, an environmentally friendly and sustainable approach, dry reactive milling, was employed to synthesize two different semiconducting oxide nanomaterials, namely TiO2 and ZnO using poly...
Hybrid assemblies based on conducting polymers and carbon nanomaterials with organized nanoscale structure are excellent candidates for various application schemes ranging from thermal management to electrochemical energy conversion and storage. In the case of macroscopic samples, however, precise control of the nanoscale structure has remained a m...
In the search for stable and efficient photocatalysts beyond TiO2 , the tungsten-based oxide semiconductors silver tungstate (Ag2 WO4 ), copper tungstate (CuWO4 ), and zinc tungstate (ZnWO4 ) were prepared using solution combustion synthesis (SCS). The tungsten precursor's influence on the product was of particular relevance to this study, and the...
Hybrid materials based on organic conjugated polymers and inorganic nanostructures have been at the leading edge of research and development. Hybridization of metal oxide semiconductors with conducting polymers is particularly interesting, since a wide range of properties can be combined with the properties of the polymer. TiO 2 , ZnO, WO 3 , Fe 3...
he aim of this study is to tailor the electrochemical synthesis of hybrid materials consisting of nanoporous tungsten trioxide (WO3) and polyaniline (PANI) for application as supercapacitor electrodes. Nanoporous WO3, synthesized by the anodization of tungsten foils, acted as the active material framework for this assembly. With the variation of th...
Photoelectrochemical synthesis of TiO2/CdX/PEDOT [X: S, Se; PEDOT = poly(3,4-ethylenedioxythiophene)] ternary hybrids was carried out by exploiting the semiconductor (SC) nature of both the oxide and the chalcogenide component. To this end, TiO2 nanotube arrays were initially electrosynthesized on titanium foils by anodization in fluoride-containin...
This work systematically investigated the relationship between structure, morphology, photoelectrochemical (PEC) and photocatalytic (PC) properties of the TiO2 catalysts. A series of TiO2 catalysts with various phase compositions (anatase-, brookite- and finally rutile-rich samples) and morphologies (1D morphology, rhomboid nanoparticles (NPs) and...