SnO2 Surface Research Articles

Adhesion, Stability and Electronic Properties of Ag/SnO2 Interface from First‐Principles Calculation

AbstractThe interfacial bonding state between each oxide and the silver matrix in AgCuOIn2O3SnO2 electrical contact materials remains unclear. To address this, first‐principles calculations using density‐functional theory are employed to establish the low‐index surfaces of Ag and SnO2 and perform convergence tests. Computational results reveal that the Ag (111) surface and the SnO2(110)‐O surface exhibit the highest stability among their respective low‐index surfaces. Consequently, these surfaces are chosen to form the interfacial model, and their atomic structure, adhesion work, and interfacial energies are systematically analyzed. The results demonstrate that the stability and interfacial bonding strength of the Ag(111)/SnO2(110)‐O interface are high, exhibiting metallic properties and strong conductivity. Moreover, at an interface spacing of d0 = 2.4 Å, the interface stability is optimal. The redistribution of charge at the interface induces significant changes in the local atomic density of states, particularly noticeable in the Ag and O atoms. Additionally, the Ag/SnO2 interface is predominantly bonded through ionic interactions, contributing to its robust bonding.

Using Atomic Layer Deposition to Create Mixed Metal Oxide Electrodes for H2O2 Generation through Water Oxidation

The electrochemical synthesis of H2O2 through water oxidation provides a means of producing a useful chemical and potential fuel without the input of fossil fuels. Highly stable metal oxides like TiO2 and SnO2 surfaces have shown activity as electrocatalysts for oxidative H2O2 generation, but often require high overpotentials that result in parasitic side reactions. Using atomic layer deposition (ALD) to introduce well-distributed layers of MnOx dopant one can lower the required overpotential of TiO2 and SnO2 surfaces for H2O2 production. Even a single sub-surface layer of MnOx can alter the redox behavior of a 5 nm thick oxide film. While the doped films maintained reversible Mn redox peaks and prevent the total dissolution of the deposited Mn, in-situ inductively coupled mass spectrometry did reveal loss of Mn from the film at applied potentials close to the expected onset potential of the 2e- water oxidation reaction. The depth of sub-surface MnOx was varied to determine the effect on both electrode activity, selectivity, and stability. In addition, the use of either inert and oxidizing annealing atmospheres was used to control both the distribution and the charge-state of the Mn species. This work provides some indication of how manganese-doped metal oxide electrodes degrade during operation and how controlling the surface can improve the activity and stability of the device. This study may also provide a framework of how other redox active species can be embedded within more stable oxide matrices using ALD methods to maximize stability and activity.

Temperature promotes selectivity during electrochemical CO2 reduction on NiO:SnO2 nanofibers.

Electrolyzers operate over a range of temperatures; hence, it is crucial to design electrocatalysts that do not compromise the product distribution unless temperature can promote selectivity. This work reports a synthetic approach based on electrospinning to produce NiO:SnO2 nanofibers (NFs) for selectively reducing CO2 to formate above room temperature. The NFs comprise compact but disjoined NiO and SnO2 nanocrystals identified with STEM. The results are attributed to the segregation of NiO and SnO2 confirmed with XRD. The NFs are evaluated for the CO2 reduction reaction (CO2RR) over various temperatures (25, 30, 35, and 40 °C). The highest faradaic efficiencies to formate (FEHCOO- ) are reached by NiO:SnO2 NFs containing 50% of NiO and 50% SnO2 (NiOSnO50NF), and 25% of NiO and 75% SnO2 (NiOSnO75NF), at an electroreduction temperature of 40 °C. At 40 °C, product distribution is assessed with in situ differential electrochemical mass spectrometry (DEMS), recognizing methane and other species, like formate, hydrogen, and carbon monoxide, identified in an electrochemical flow cell. XPS and EELS unveiled the FEHCOO- variations due to a synergistic effect between Ni and Sn. DFT-based calculations reveal the superior thermodynamic stability of Ni-containing SnO2 systems towards CO2RR over the pure oxide systems. Furthermore, computational surface Pourbaix diagrams showed that the presence of Ni as a surface dopant increases the reduction of the SnO2 surface and enables the production of formate. Our results highlight the synergy between NiO and SnO2, which can promote the electroreduction of CO2 at temperatures above room temperature.

Efficiency improvement of antimony selenide solar cells based on S-doped SnO2 buffer layer

Antimony Selenide (Sb2Se3) exhibits potential as a solar energy material owing to its optimal bandgap, lack of toxicity, and abundance of earth abundant elements. Currently, cadmium sulfide (CdS) serves as the predominant buffer layer for Sb2Se3 solar cells. However, the use of CdS hinders environmentally friendly advancement due to the toxic properties of the element cadmium. Hence, the quest for non-toxic buffer layers poses a significant challenge to the further advancement of Sb2Se3 solar cells. In prior research, tin oxide (SnO2) has been explored as a buffer layer. Nonetheless, the efficiency of SnO2/Sb2Se3 solar cells was hampered by the rough surface of SnO2 films and the poor crystallinity of Sb2Se3 films. In this investigation, we enhanced device efficiency by improving the uniformity of the SnO2 surface and enhancing the crystallinity of Sb2Se3 through spin-coating sulfur (S) onto the SnO2 film. Detailed examinations were conducted on the structure, optical, and electrical properties of the respective SnO2 and Sb2Se3 thin films. Ultimately, an efficiency of 3.38% was achieved using the spin-coated S:SnO2 film, marking an 85% enhancement compared to the baseline device.

How the Interplay between SnO2 and Zn(II) Porphyrins Impacts on the Electronic Features of Gaseous Acetone Chemiresistors.

Herein, the integration of SnO2 nanoparticles with two Zn(II) porphyrins─Zn(II) 5,10,15,20-tetraphenylporphyrin (ZnTPP) and its perfluorinated counterpart, Zn(II) 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (ZnTPPF20)─was investigated for the sensing of gaseous acetone at 120 °C, adopting three Zn-porphyrin/SnO2 weight ratios (1:4, 1:32, and 1:64). For the first time, we were able to provide evidence of the correlation between the materials' conductivity and these nanocomposites' sensing performances, obtaining optimal results with a 1:32 ratio for ZnTPPF20/SnO2 and showcasing a remarkable detection limit of 200 ppb together with a boosted sensing signal with respect to bare SnO2. To delve deeper, the combination of experimental data with density functional theory calculations unveiled an electron-donating behavior of both porphyrins when interacting with tin dioxide semiconductor, especially for the nonfluorinated one. The study suggested that the interplay between electrons injected, from the porphyrins' highest occupied molecular orbital to SnO2 conduction band, and the latter's available electronic states has a dramatic impact to boost the chemiresistive sensing. Indeed, we highlighted that the key lies in preventing the full saturation of SnO2 electronic states concomitantly increasing the materials' conductivity: in this respect, the best compromise turned out to be the perfluorinated porphyrin. A further corroboration of our findings was obtained by illuminating the sensors during measurements with light-emitting diode (LED) light. Actually, we demonstrated that it does not have any impact on improving the sensing behavior, most probably due to the electronic oversaturation and scattering caused by LED excitation in porphyrins. Lastly, the most effective hybrids (1:32 ratio) were physicochemically characterized, confirming the physisorption of the macrocycles onto the SnO2 surface. In conclusion, herein, we underscore the feasibility of customizing the porphyrin chemistry and porphyrin-to-SnO2 ratio to enhance the gaseous sensing of bare metal oxides, providing valuable insights for the engineering of highly performing light-free chemiresistors.

Target therapy at buried interfaces toward efficient and stable inorganic perovskite solar cells

The enhancement of power conversion efficiency (PCE) of perovskite solar cells (PSCs) is critically affected by charge recombination induced by buried interface defects. In light of this, a simple and effective target therapy strategy has been developed by doping 4-(diphenylphosphino)benzoic acid (4DBA) molecules at the tin oxide (SnO2)/perovskite interface. The effects of 4DBA on carrier transport, perovskite growth, defect passivation, and PSCs properties were systematically investigated. It is illustrated that 4DBA molecules not only passivate oxygen vacancy (OV) defects on the SnO2 surface, enhancing the conductivity of the SnO2 film and accelerating electron transfer, but also passivate perovskite interface defects, thereby improving the quality of the perovskite film. Ultimately, the efficiency of CsPbBr3 device with 4DBA-modified buried interface increased from 8.87% to 10.78%, an improvement of 21.53%. Furthermore, the efficiency of CsPbI2Br increased from 12.83% to 14.44%, an improvement of 12.55%, further demonstrating the effectiveness and universality of this strategy. Excitingly, the unencapsulated PSCs exhibit excellent long-term stability under high relative humidity and high temperatures.

Energy Band-Modulated SnO Anodes with Improved Rate Capacity and Initial Coulombic Efficiency for Sodium-Ion Batteries.

An efficient interface and composition modification strategy is proposed to significantly increase the rate capacity and initial Coulombic efficiency (ICE) of SnO anodes via energy band structure modulation for Na-ion batteries (SIBs). The as-fabricated SnO@Bi@C material with Bi nanocrystals homogeneously dispersed on and around the SnO surface is prepared by an electrospinning method. The excellently dispersed Bi nanocrystals realize an effective interface contact with SnO and Na2O, which effectively lowers the electron conduction barriers and promotes sodium-ion release and transport upon the desodiation process, increasing the rate capacity and ICE of the SnO anode. The prepared SnO@Bi@C exhibits a much higher rate capacity up to 10 A g-1, except an improved ICE of 80.67%, compared to 57.38% of SnO@C. Importantly, the intercalation of Na+ between layer-structured Bi galleries provides a good basis for excellent cycle stability due to the highways constructed inside the prepared composites. This finding provides an effective tactic to establish ion transport high-speed channels, which essentially increase the rate performance and the ICE of the SnO-based anodes.

Post‐Treated Polycrystalline SnO2 in Perovskite Solar Cells for High Efficiency and Quasi‐Steady‐State‐IV Stability

AbstractThe prominent chemical bath deposition (CBD) method leverages tin dioxide (SnO2) as an electron transport layer (ETL) in perovskite solar cells (PSCs), achieving exceptional efficiency. The deposition of SnO2, however, can lead to the formation of oxygen vacancies and surface defects, which subsequently contribute to performance challenges such as hysteresis and instability under light‐soaking conditions. To alleviate these issues, it is crucial to address heterointerface defects and ensure the uniform coverage of SnO2 on fluorine‐doped tin oxide substrates. Herein, the efficacy of tin(IV) chloride (SnCl4) post‐treatment in enhancing the properties of the SnO2‐ETL and the performances of PSCs are presented. The treatment with SnCl4 not only removes undesired agglomerated SnO2 nanoparticles from the surface of CBD SnO2 but also improves its crystallinity through a recrystallization process. This leads to an optimized interface between the SnO2‐ETL and perovskite, effectively minimizing defects while promoting efficient electron transport. The resultant PSCs demonstrate improved performance, achieving an efficiency of 25.56% (certified with 24.92%), while retaining 95.84% of the initial PCE under ambient storage conditions. Additionally, PSCs treated with SnCl4 endure prolonged light‐soaking tests, particularly when subjected to quasi‐steady‐state‐IV measurements. This highlights the potential of SnCl4 treatment as a promising strategy for advancing PSC technology.

Modified SnO2 Electron Transport Layer by One‐Step Doping with Histidine in Perovskite Solar Cells

Tin dioxide (SnO2), one of the best electron transport layer materials for perovskite solar cells (PSCs), has high electrical conductivity and low photocatalytic activity. However, the defects in its inside and surface result in nonradiative recombination at the SnO2/perovskite interface. Complex and time‐consuming passivation methods are not conducive to the commercialization of PSCs, and simple passivation strategies should be used to improve the photovoltaic performance of the devices. Herein, a facile and efficient method is proposed to simultaneously passivate the inside and surface defects by adding histidine (HIS) to SnO2 colloidal solution. This one‐step doping strategy also modulates carrier dynamics at the SnO2/perovskite interface. HIS reduces suspended hydroxyl groups, oxygen vacancies, and uncoordinated Sn4+ defects on the surface of SnO2, as well as uncoordinated Pb2+ and halogen vacancy defects at the buried interface of perovskite. Surprisingly, HIS can prevent perovskite from decomposition to form PbI2, which further decomposes to photoactive metallic Pb0 and I, causing ion migration in PSC. As a result, the PSC efficiency has significantly improved 23.11% after HIS doping. The efficiency of unencapsulated device with HIS is 94% of the primary efficiency after storage in relative humidity = 70 ± 5% for 1000 h.

Sub-ppm short-chain fatty acids detection with La(III) modified SnO2 gas sensors

La(III) modified nanocrystalline SnO2 with lanthanum content [La]/([Sn] +[La]) = 0; 0.5; 1 and 2 mol. % were prepared by flame spray pyrolysis and characterized by X-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Identification of surface segregation of La(III) containing phases was performed via Raman spectroscopy. Acidic properties of pure and La(III) modified SnO2 were characterized by temperature-programmed desorption of ammonia (TPD-NH3) with mass spectral determination of desorption products. It was demonstrated that decrease in the Lewis acidity of the SnO2 surface leads to the specific increase in sensor response when detecting gases with acidic properties like short-chain fatty acids (SCFAs) and H2S. The obtained materials are capable to detect SCFAs at ppb concentration level, including high air humidity conditions (RH = 80 %).

Vacancy-Rich SnO2 Quantum Dot Stabilized by Polyoxomolybdate as Electrocatalyst for Selective NH3 Production.

The pronounced conductivity of tin dioxide (SnO2) nanoparticles makes it an ideal multifunctional electrode material, while the challenge is to stabilize the quantum dot (QD) SnO2 nanocore in water. An Anderson-type polyoxomolybdate, (NH4)6[Mo7O24], is employed as an inorganic ligand to stabilize a ca. 6 nm SnO2 QD (Mox@SnO2). X-ray scattering and diffraction studies confirm the tetragonal SnO2 nanocore in Mox@SnO2. Elemental analyses are in good agreement with the mass spectrometric detection of the [Mo7O24]6- cluster present in Mox@SnO2. The ionic POMs attached to the SnO2 surface through [Mo-O-Sn] covalent linkages have been established by surface zeta potential, shift of the [Mo = O]t Raman vibration, and extended X-ray absorption fine structure (EXAFS) analyses. The presence of the [Mo7O24]6- cluster in the Mox@SnO2 is responsible for the remarkable aqueous stability of Mox@SnO2 in the pH range of 3-9. Dominant oxygen vacancy in the SnO2 core, identified by EXAFS data and the anisotropic electron paramagnetic resonance (EPR) signals (g ∼ 2.4 and 1.9), results in facile electronic conduction in Mox@SnO2 while being deposited on the electrode surface. Mox@SnO2 acts as an active catalyst for the electrocatalytic nitrate reduction (eNOR) to ammonia with 94% faradaic efficiency (FE) at -0.2 V vs RHE and a yield rate of 28.9 mg h-1 cm-2. The stability of Mox@SnO2 in acidic pH provides scope to reuse the Mox@SnO2 electrode at least four times with notable NH3 selectivity and a superior production rate (239.06 mmol g-1(cat) h-1). This study demonstrates the essential role of POM in stabilizing SnO2 QD, harnessing its electrochemical activity toward electrocatalytic ammonia production.

Ce-Doped SnO2 Electron Transport Layer for Minimizing Open Circuit Voltage Loss in Lead Perovskite Solar Cells.

In the planar heterostructure of perovskite-based solar cells (PSCs), tin oxide (SnO2) is a material that is often used as the electron transport layer (ETL). SnO2 ETL exhibits favorable optical and electrical properties in the PSC structures. Nevertheless, the open circuit voltage (VOC) depletion occurs in PSCs due to the defects arising from the high oxygen vacancy on the SnO2 surface and the deeper conduction band (CB) energy level of SnO2. In this research, a cerium (Ce) dopant was introduced in SnO2 (Ce-SnO2) to suppress the VOC loss of the PSCs. The CB minimum of SnO2 was shifted closer to that of the perovskite after the Ce doping. Besides, the Ce doping effectively passivated the surface defects on SnO2 as well as improved the electron transport velocity by the Ce-SnO2. These results enabled the power conversion efficiency (PCE) to increase from 21.1% (SnO2) to 23.0% (Ce-SnO2) of the PSCs (0.09 cm2 active area) with around 100 mV of improved VOC and reduced hysteresis. Also, the Ce-SnO2 ETL-based large area (1.0 cm2) PSCs delivered the highest PCE of 22.9%. Furthermore, a VOC of 1.19 V with a PCE of 23.3% was demonstrated by Ce-SnO2 ETL-based PSCs (0.09 cm2 active area) that were treated with 2-phenethylamine hydroiodide on the perovskite top surface. Notably, the unencapsulated Ce-SnO2 ETL-based PSC was able to maintain above 90% of its initial PCE for around 2000 h which was stored under room temperature condition (23-25 °C) with a relative humidity of 40-50%.

An MBene Modulating the Buried SnO2/Perovskite Interface in Perovskite Solar Cells

AbstractThe interface of perovskite solar cells (PSCs) plays an important role in transferring and collecting charges. Interface defects are important factors affecting the efficiency and stability of PSCs. Here, the buried interface between SnO2 and the perovskite layer is bridged by two‐dimensional (2D) MBene, which improves charge transfer. MBene can deposit additional electrons on the surface of SnO2, passivate its surface defects and facilitate the charge collection. Moreover, the dipole moment formed at the interface increases the electron transfer ability in the PSCs. MBene also regulates the growth of perovskite crystals, improves the quality of perovskite films, and reduces its grain boundary defects. As a result, PSCs based on FA0.2MA0.8PbI3 and (FAPbI3)0.95(MAPbBr3)0.05 get the enhanced efficiencies of 22.34 % and 24.32 % with negligible hysteresis. Furthermore, the optimized device exhibits better stability. This work opens up the application of MBene materials in PSCs, reveals a deeper understanding of the mechanism behind using 2D materials as an interface modification layer, and shows opportunities for using MBene as potential material in photoelectric devices.

An MBene Modulating the Buried SnO2/Perovskite Interface in Perovskite Solar Cells.

The interface of perovskite solar cells (PSCs) plays an important role in transferring and collecting charges. Interface defects are important factors affecting the efficiency and stability of PSCs. Here, the buried interface between SnO2 and the perovskite layer is bridged by two-dimensional (2D) MBene, which improves charge transfer. MBene can deposit additional electrons on the surface of SnO2, passivate its surface defects and facilitate the charge collection. Moreover, the dipole moment formed at the interface increases the electron transfer ability in the PSCs. MBene also regulates the growth of perovskite crystals, improves the quality of perovskite films, and reduces its grain boundary defects. As a result, PSCs based on FA0.2MA0.8PbI3 and (FAPbI3)0.95(MAPbBr3)0.05 get the enhanced efficiencies of 22.34 % and 24.32 % with negligible hysteresis. Furthermore, the optimized device exhibits better stability. This work opens up the application of MBene materials in PSCs, reveals a deeper understanding of the mechanism behind using 2D materials as an interface modification layer, and shows opportunities for using MBene as potential material in photoelectric devices.

Insight of hydrogen evolution reaction in slab SnO2 loaded with transition metal atoms

The utilization of hydrogen energy has emerged as a promising solution for clean and sustainable energy sources. The development of cost-effective catalysts with high activity and stability is crucial for efficient hydrogen production. In this work, we investigated the hydrogen evolution reaction (HER) catalytic activity of single transition metal atom (TM = V, Cr, Mn, Fe, Co, Ni) on slab SnO2 by using density functional theory. Our results revealed that the catalytic activity of the slab SnO2 can be significantly enhanced by loading the transition atom. By calculating the Gibbs free energies and exchange current densities in different adsorption configurations of TM-SnO2, single-atom catalyst (SAC) of Mn-loaded SAC exhibits excellent catalytic performance, characterized by a low Gibbs free energy barrier (−0.05 eV). Introducing a TM on the SnO2 surface breaks its local symmetry, while the strong coupling between the metal and H atoms enhances catalytic performance. The synergetic effect of symmetry breaking and metal-H interaction boosts overall catalytic activity. This work not only proposes a novel non-platinum HER catalyst based on SnO2 but also lays a solid foundation for future applications of SnO2-based catalysts.

Enhanced electrocatalytic CO2 reduction through constructing chemically homogeneous interfaces via ultrathin carbon encapsulated tin oxide

Electrocatalytic CO2 reduction to high-value chemicals has significant potential to combat environmental and energy crises. The strength and mode of adsorption of reaction species play a crucial role in determining the CO2 reduction products. Therefore, it is vital to construct catalytic interfaces with high catalytic activity, selectivity and chemically homogeneous for efficient CO2 reduction. Herein, ultra-thin carbon layer encapsulated sub-5 nm SnO2 quantum dots (SnO2@u-C) has been prepared by Sn-MOFs derivation for efficient electrocatalytic CO2 reduction. Specifically, the Faradaic efficiency of formate (FEformate) and energy efficiency of formate production (EEformate) exceed 80 % and 50 % respectively, over a wide potential range, with the highest value reaching 95.7 % for FEformate and 58.2 % for EEformate. Moreover, SnO2@u-C electrode shows excellent stability over 10 h with FEformate about 89 % at −1.17 V versus reversible hydrogen electrode. DFT calculations and experimental characterization reveal that the ultrathin carbon layer coating on the surface of SnO2 forms a chemically homogeneous catalytic interface, facilitating the adsorption and conversion of reaction species to achieve exceptional formate selectivity. Moreover, the carbon layer builds a three-dimensional rapid electron conduction network that supports electron transfer to CO2 molecules and suppressing SnO2 reduction.

Surface Engineering of Tin Oxide Nanoparticles by pH Modulation Facilitates Homogeneous Film Formation for Efficient Perovskite Solar Modules

AbstractUniform film deposition over an entire substrate is indispensable to achieve efficient perovskite solar modules (PSMs) by minimizing the gap with high‐performance perovskite solar cells (PSCs). Only a few microscopic pinholes on the film in PSMs directly give rise to debase the performance and stimulate the degradation of the devices. Herein, a strategy of the homogeneous and defect‐reduced electron‐transport layer for high‐performance PSMs is reported. pH modulation of tin oxide (SnO2) nanoparticles colloidal dispersion by a small amount of nitric acid (HNO3) addition leads to the removal of hydroxy groups on the SnO2 surface acting as electronic defects as well as superb regularity of the thin films by forming a network of the SnO2 nanoparticles. The surface engineering of SnO2 nanoparticles brings out the high performance of 23.7% efficiency for a unit cell, 20.3% efficiency for a 24.5 cm2 minimodule, and 19.0% efficiency for a 214.7 cm2 submodule, respectively, where all efficiencies are averaged from results obtained by the reverse/forward scan. In outdoor tests with the submodules, a target PSM generates 16.5% higher cumulative electricity for a month as compared to a control PSM. Furthermore, under damp heat environments, the target PSM maintains 80% efficiency compared to an initial efficiency of 1080 h.

Pt-substituted rutile SnO2 (110) surface: first-principles study on its adsorption of formaldehyde

Pt-substituted rutile SnO2 (110) surface: first-principles study on its adsorption of formaldehyde

Benzalkonium chloride modification of tin oxide to enhance the performance of perovskite solar cells

For planar perovskite solar cells (PSCs), tin oxide (SnO2) is a perfect electron transport material. However, owing to nanoparticle agglomeration and defects, the advantages of SnO2 cannot be effectively utilized. Herein, a cationic surfactant, benzalkonium chloride (BAC) is introduced into SnO2 precursor solution to prevent the aggregation of SnO2. Thus, a uniform and free of pinhole SnO2 electron transport layer (ETL) is obtained, which supports the formation of high-quality perovskite layer (PVK). The introduction of BAC adjusts the energy level of ETL and improves the electron transport in the buried interface. Moreover, the BAC-modification reduces and passivates the defects on the surface of SnO2 and perovskite films. Consequently, BAC-modified PSCs achieves a champion efficiency of 23.49 % with an impressive fill factor of 84.50 %. The unpackaged device maintains an initial efficiency of 91.4 % after 1000 h of storage in dark at 25 ± 5 °C and 25 ± 5 % relative humidity.

Redox properties of PbO2, IrO2 and SnO2 (110) surfaces with an adsorbed OH molecule: a chemical reactivity study in the grand canonical ensemble

Redox properties of PbO2, IrO2 and SnO2 (110) surfaces with an adsorbed OH molecule: a chemical reactivity study in the grand canonical ensemble