Wei Cao

Wei Cao
University of Oulu · Nano and Molecular Systems Research Unit

Dr. Rer. Nat; Docent

About

187
Publications
20,766
Reads
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2,078
Citations
Additional affiliations
February 2019 - January 2024
University of Oulu
Position
  • Professor (Associate)

Publications

Publications (187)
Article
Full-text available
As one of the most important hosts of natural light harvesting, foliage normally has complicated surface structures to capture solar radiances. Bio-mimicking leaf surface structures can provide novel designs of covers in photovoltaic systems. In this article, we reported on replicating leaf surface structures on poly-(methyl methacrylate) polymers...
Article
Electron spins of the doped monolayer MoS2 were aligned by placing two magnetic impurities at sulfur vacancies, both on the same side and different sides of the slab. Origins of the calculated magnetisms are beyond most conventional physical models, yet interactions of single-molecule magnets are tentatively proposed.
Article
A critical factor for electronics based on inorganic layered crystals stems from the electrical contact mode between the semiconducting crystals and the metal counterparts in the electric circuit. Here, a materials tailoring strategy via nanocomposite decoration is carried out to reach metallic contact between MoS2 matrix and transition metal nanop...
Article
Full-text available
The widely used stainless steels and their deformed variants are anticorrosive in ambient conditions due to passivation layers composed of chromium oxides. Conventionally, corrosion and erosion of the steels are attributed to the breakdown of such layers but seldomly to the origin that depends on surface heterogeneity at the microscopic level. In t...
Article
Synthesis is the base of experimental chemistry. Herein, monodisperse K3PMo12O40▪nH2O polyoxometalates (POMs) with different morphologies have been reached by tuning synthetic conditions of the K/POM ratio, stirring speed and time, and reaction temperatures. Among these factors, the K/POM ratio is identified most critical in morphological controls...
Article
Though carbonates are known for several decades, their role in sun-light driven photocatalysis is still hidden. Herein, carbonate boosted solar water splitting in nickel-based plasmonic hybrid nanostructures is disclosed for the first time via in-situ experiments and density-functional theory (DFT)-based calculations. [email protected]/NiCO3 [email...
Article
Despite the boom in catalytic response via constructing interfaces, understanding interfaces’ interaction in heterostructures is still a paradox. In this work, the interaction of Ni with MoS2 in Ni-Ag-MoS2 heterostructure are unveiled through synchrotron X-PEEM and what’s more, the missing interaction mechanism at the Ag-MoS2 interface is probed vi...
Article
Cobalt-based hydroxide are ideal candidates for the oxygen evolution reaction. Herein, we use molybdenum oxide nanorods as sacrificial templates to construct a self-supporting molybdenum-doped cobalt hydroxide nanosheet hierarchical microtubule structure based on a structural engineering strategy to improve the active area of the catalyst. X-ray-ba...
Article
The overwhelming impact of complex-phase microstructures on mechanical response in multiphase steels requires accurate constitutive properties of the individual phases. However, precise prediction of individual phase properties on their mechanical response is critical and sophisticated, which commonly requires multiscale characterizations and numer...
Article
The microstructure, mechanical properties, and corrosion resistance to simulated body fluid solution behavior of as-extruded Mg-1.8Zn-0.5Zr alloys with different Gd additions are investigated. It is found that dynamic recrystallization occurs in the alloys during extrusion and the grain size gradually decreases with Gd alloying. The mechanical prop...
Preprint
Full-text available
A large number of novel two-dimensional (2D) materials are constantly discovered and deposed into the databases. Consolidate implementation of machine learning algorithms and density functional theory (DFT) based predictions have allowed creating several databases containing an unimaginable amount of 2D samples. The next step in this chain, the inv...
Article
Full-text available
Direct sunlight-induced water splitting for photocatalytic hydrogen evolution is the dream for an ultimate clean energy source. So far, typical photocatalysts require a complicated synthesis process and barely work without additives or electrolytes. Here we report the realization of a hydrogen evolution strategy with novel MoS2-Ag-Ni ternary nanoca...
Article
Full-text available
The crystallization in glasses is a paradoxical phenomenon and scarcely investigated. This work explores the non-isothermal crystallization of a multicomponent alumino-borosilicate glass via in situ high-energy synchrotron X-ray diffraction, atomic pair distribution function, and Raman spectroscopy. Results depict the crystallization sequence as Ca...
Preprint
Full-text available
Reactive magnesium oxide (MgO)-based cement (RMC) can play a key role in carbon capture processes. However, knowledge on the driving forces that control the degree of carbonation and hydration and rate of reactions in this system remains limited. In this work, density functional theory-based simulations are used to investigate the physical nature o...
Article
The effect of surface nanocrystallization produced by laser shock processing (LSP) on the corrosion fatigue behavior of 300M steel was systematically investigated. The surface integrity, microstructure evolution and residual stresses before and after corrosion fatigue were characterized. The results showed that afte LSP the surface grain size of 30...
Article
The surface treatment of Ti80 alloy with different microstructures was performed by laser shock peening (LSP), and the effect of LSP on Ti80 alloy on microstructure and corrosion properties was investigated. After LSP, the surface grains of Ti80 alloy with different microstructures were all refined, microhardness was significantly increased, and co...
Article
Full-text available
Reactive magnesium oxide (MgO)-based cement (RMC) can play a key role in carbon capture processes. However, knowledge on the driving forces that control the degree of carbonation and hydration and rate of reactions in this system remains limited. In this work, density functional theory-based simulations are used to investigate the physical nature o...
Article
In this work, the surface modification of Ti-6Al-3Nb-2Zr-1Mo (Ti80) alloy was performed by laser shock peening (LSP). The resultant microstructure, mechanical properties and corrosion properties of LSP-treated (LSPed) Ti80 were systematically investigated by 3D profiler, x-ray diffractometer (XRD), optical microscope (OM), transmission electron mic...
Article
Full-text available
A large number of novel two-dimensional (2D) materials are constantly being discovered and deposited in databases. Consolidated implementation of machine learning algorithms and density functional theory (DFT)-based predictions have allowed the creation of several databases containing an unimaginable number of 2D samples. As the next step in this c...
Article
Despite the common challenge of investigating non-metallic inclusions within ultra-high-strength-steel (UHSS) at sub-micrometer scale via conventional methods, probing nitride inclusions at elevated temperatures is vital for guiding steel’ performance. Herein, an in-situ spectro-microscopic determination using advanced Synchrotron X-ray absorption...
Article
Non-metallic inclusions play a decisive role in the steel's performance. Therefore, their determination and control over their formation are crucial to engineer ultra-high-strength steel. Currently, bare experimental approaches are limited in the identification of non-metallic inclusions within microstructural phases of complex steel matrices. Here...
Article
Phase transformation in low alloyed Fe-C steels during quenching and partitioning (Q&P), though authentically attributed to carbon diffusion, is scarcely quantified experimentally in terms of microstructural evolution and lack of fundamental backing at a quantum mechanics level. Herein, we report on a combined in-situ high energy synchrotron X-ray...
Article
Full-text available
Iron aluminide (FeAl) inter-metallic compounds are potential candidates for structural applications at high temperatures owing to their superior corrosion resistance, high temperature oxidation, low density and inexpensive material cost. However, the presence of defects can lead to reduction in the strength and ductility of FeAl-based materials. He...
Article
Gradient nanostructures (GNs) were created in 300M ultra-high strength (UHS) steel by laser shock processing (LSP). Microstructure evolution and properties of GNs subjected to LSP with different pulse energies were thoroughly characterized on 3D profiler, scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffractomet...
Article
Full-text available
In this work, the unique plastic deformation behavior of T2 rolled copper foils under ultrasonic impact (UI) and ultrasonic rolling (UR) has been studied systematically. The numerical simulation and test results show that with the decrease of the thickness of copper sheet, the equivalent plastic strain (PEEQ) value and plastic strain εp formed by U...
Article
Full-text available
There is some ambiguity regarding the fate of Mg during the alkali activation of Mg-rich precursors within the broader field of alkali activated materials (AAMs). The present work addresses this issue by studying the reaction products in AAMs synthesized from (Na-Mg) aluminosilicate glasses. Here, instead of magnesium silicate hydrate (M-S-H) phase...
Article
In this work, supersonic fine particle bombardment (SFPB) was applied to modify surface of TC11 alloy and its impacts on microstructure and fatigue properties were systematically studied. The modified surface owned a nanoscale grain structure and a compressive residual stress with an amplitude of -196 MPa. The depth of hardened layer was about 300...
Article
Full-text available
As-extruded Mg-1.8Zn-0.5Zr-xGd alloys are thoroughly investigated for their microstructure, mechanical properties and degradation behavior in a wide range of minor Gd alloying (0 ≤ x ≤ 2.5 wt%). These alloys show complete dynamic recrystallization when the extrusion ratio and extrusion temperature are 7.7 and 350 °C, respectively. The resultant gra...
Article
Supersonic fine particles bombarding (SFPB) technology opens a new territory for engineering materials towards improved performances. Owing to its merits and emerging applications, 300M steel (tensile strength ≥1800 MPa) was treated with SFPB to create surface gradient nanostructures. The time dependent SFPB process was implemented on various 300M...
Article
The preparation of oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) catalysts with high activity, stability and low platinum loading has always been the focus of research. The single-atom platinum supported catalyst greatly improves the utilization of platinum, but the catalytic activity and selectivity are greatly affected by...
Article
Full-text available
Niobate perovskites like the (K,Na)NbO3 (KNN) family are among the most important lead-free ferroelectrics. Ba and Ni have been co-doped into KNN to induce Ni²⁺-oxygen vacancy defect dipoles to significantly reduce the band gap while maintaining the ferroelectricity. This opens doors to novel optoferroelectric applications such as multisensors and...
Preprint
The existence of two novel hybrid two-dimensional (2D) monolayers, 2D B3C2P3 and 2D B2C4P2, has been predicted based on the density functional theory calculations. It has been shown that these materials possess structural and thermodynamic stability. 2D B3C2P3 is a moderate band gap semiconductor, while 2D B2C4P2 is a zero band gap semiconductor. I...
Article
Full-text available
The structure of CaO‐Al2O3‐B2O3‐BaO glassy slags with varying mass ratio of BaO to CaO has been investigated by Raman spectroscopy, 11B and 27Al magic angular spinning nuclear magnetic resonance (MAS‐NMR) spectroscopy and atomic pair distribution function (PDF). 11B MAS‐NMR spectra reveal the dominant coordination of boron as trigonal. Both simulat...
Article
The existence of two novel hybrid two-dimensional (2D) monolayers, 2D B3C2P3 and 2D B2C4P2, has been predicted based on the density functional theory calculations. It has been shown that these materials possess structural and thermodynamic stability. 2D B3C2P3 is a moderate band gap semiconductor, while 2D B2C4P2 is a zero band gap semiconductor. I...
Preprint
Density functional theory based computational study has been conducted in order to investigate the effect of substitution of Cr and Co components by Si on the structure, mechanical, electronic, and magnetic properties of the high entropy alloy CrCoNiFe. It is found that the presence of a moderate concentration of Si substitutes (up to 12.5 %) does...
Article
ZrB2‐SiC ceramics and Nb alloy were brazed at 1160°C for 60 min with CoFeNiCrCuTix high‐entropy alloy filler. The influence of Ti content on the interface structure and mechanical properties of ZrB2‐SiC/Nb joint was systematically studied. It is found that the rich‐Ti Laves phase was formed due to the addition of large atomic size Ti fill into the...
Article
Determining non-metallic inclusions (NMIs) are essential to engineer ultra-high-strength steel as they play decisive role on performance and critical to probe via conventional techniques. Herein, advanced Synchrotron X-ray absorption coupled with photoemission electron microscopy and first-principles calculations are employed to provide the structu...
Article
Full-text available
The stabilization of a hexagonal phase known as the ω-phase in steel has recently been identified. The presence of C in steel samples is found to be helping the formation of this otherwise meta stable phase. This indicates that the probability of degradation of the surface is high in steel samples containing the ω-phase, through surface adsorption....
Article
Ni@NiO/NiCO3 core–shell nanostructures have been investigated for surface plasmon driven photocatalytic solar H2 generation without any co-catalyst. Huge variation in the photocatalytic activity has been observed in the pristine vs. post-vacuum annealed samples with the maximum H2 yield (∼110 μmol g−1 h−1) for the vacuum annealed sample (N70-100/2...
Article
Density functional theory based computational study has been conducted in order to investigate the effect of substitution of Cr and Co components by Si on the structure, mechanical, electronic, and magnetic properties of CrCoNiFe. It is found that the presence of a moderate concentration of Si substitutes (up to 12.5 %) does not significantly reduc...
Article
Quenching and partitioning produces advanced high-strength steels that utilise transformation-induced plasticity for improved strength and deformability. Microstructures of these steels consist mainly of tempered martensite and carbon-enriched retained austenite. A novel processing route of direct-quenching and partitioning (DQP) facilitates carbon...
Article
Recent advances in transmission electron microscopy (TEM) in respect of structural characterization down to atomic scale have enabled confirmation of stabilization of long ignored hexagonal omega ( ω ) phase in steel. The presence of ω phase is suggested to increase the strength of steel, and one of the factors concerning its stabilization is enric...
Article
Full-text available
Alkali-activated materials (AAMs), sometimes called geopolymers, are eco-friendly cementitious materials with reduced carbon emissions when compared to ordinary Portland cement. However, the availability of most precursors used for AAM production may decline in the future because of changes in industrial sectors. Thus, new precursors must be develo...
Conference Paper
Recent advances in transmission electron microscopy (TEM) in respect of structural characterization down to atomic scale have enabled confirmation of stabilization of long ignored hexagonal omega (ω) phase in steel. The presence of ω phase is suggested to increase the strength of steel, and one of the factors concerning its stabilization is enrichm...
Conference Paper
Quenching and partitioning produces advanced high-strength steels that utilise transformation-induced plasticity for improved strength and deformability. Microstructures of these steels consist mainly of tempered martensite and carbon-enriched retained austenite. A novel processing route of direct-quenching and partitioning (DQP) facilitates carbon...
Article
Though the availability of solar energy is predicted for centuries, the diurnal and asymmetrical nature of the sun across the globe presents significant challenges in terms of harvesting sunlight. Photo/electro-catalysis, currently believed to be the bottleneck, promises a potential solution to these challenges along with a green and sustainable en...
Article
Full-text available
P25 comprising of mixed anatase and rutile phases is known to be highly photocatalytically active compared to the individual phases. Using a facile wet chemical method, we demonstrate a ternary nanocomposite consisting of Ni and Ag nanoparticles, decorated on the surface of XTiO2 (X: P25, rutile (R)) as an efficient visible-light-driven photocataly...
Article
Full-text available
Stress relief treatments were carried out separately with a pneumatic chipping hammer, ultrasonic peening treatment, and heat treatment for metal active-gas welding (MAG) welded joints of 2205 duplex stainless steel. The effects of these methods on the residual stress, microstructure, mechanical properties and corrosion resistance of welded joints...
Article
Thermomechanical deformation is one of the most efficient and facile routes to tailor microstructure in structural materials for mechanical property enhancement. In this work, the Ce‐modified SAF2507 super duplex stainless steel (Ce‐SAF2507) was deformed at different levels from 30% to 90% at a cryogenic temperature (‐196 oC) to achieve superior me...
Article
New structures made on the basis of CZTS by substitution with Cr, Ti, V, and Mo were investigated by using density functional theory. The total substitution of Zn by Cr and V leads to the vanish of the bandgap, while n-type conductivity with the low bandgap of 0.19 eV was predicted in the case Ti. In addition, conduction band minimum and valence ba...
Article
Full-text available
Aluminosilicate glasses are materials with a wide range of technological applications. The field strength of network-modifying cations strongly influences the structure of aluminosilicate glasses and their suitability for various applications. In this work, we study the influence of the field strength of network-modifying cations on the structure o...
Article
ZrB2-SiC ceramic and Nb were brazed by using a novel high entropy alloy CoFeNiCrCu filler. Interfacial microstructure, mechanical properties and brazing mechanism of the joint were systematically investigated. It was found that the activity of Cr could be maintained during the brazing process due to the high-entropy mixing effect of CoFeNiCrCu. The...
Article
The naturally evolved sunlight harvesters are not limited to foliage. Animals also harvest sunlight for light-heat conversion. A typical antireflective and light-trapping scheme has been well demonstrated on thin butterfly scales where solar energy is converted to heat besides being diffracted for surface coloration. Biomimicking scale structures o...
Article
Full-text available
A typical rare-earth element modified Ce-SAF 2507 super duplex stainless steel was isothermally hot-compressed to reach superior mechanic properties over its pristine and peers. Mechanical, macro- and micro-structural evolutions subjected to hot-modification were studied in detail toward an optimal hot working for the Ce-SAF2507. A dynamic softenin...
Article
Full-text available
In this study, the carbon fiber reinforced ZrB2-SiC composite ceramic was joined to Ti6Al4V alloy with Ag-Cu eutectic alloy filler at varied holding time and a fixed temperature of 800℃. Interface microstructure and shear strength of brazing joints were studied. The brazed ZSCf ceramics/AgCu/TC4 alloy is endowed with good metallurgical bondings. A...
Article
Tungsten trioxide hydrate (WO3⋅1/3H2O) nanoparticles (NPs) were prepared via a microwave–assisted synthetic pathway by using Na2WO4·2H2O and PdCl2 as precursors. Microstructure and morphology of as–prepared WO3⋅1/3H2O NPs were investigated through X–ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared (FT–IR...
Article
The recently fabricated two-dimensional phosphorus carbide (PC) has been proposed for application in different nanodevices such as nanoantennas and field-effect transistors. However, the effect of ambient molecules on the properties of PC and, hence, the productivity of PC-based devices is still unknown. Herein a first-principles investigation is p...
Article
Full-text available
Photocatalysis technology has risen to effectively degrade the hardly-degraded organic pollutants in recent years and the photocatalysts play an important role in striding the obstacles of the visible light response. Herein, a high-efficiency BiVO4/Bi5O7I heterojunctional photocatalysts have been purposefully designed by controlling the reactant ra...
Article
Niobium oxalate was employed to obtain BiNbO4 for the first time and the BiNbO4 nanorods were successfully synthesized through a hydrothermal method at a low temperature. Oxygen vacancies were introduced into the BiNbO4 nanorods, lowering the BiNbO4 bandgap. The O-deficient BiNbO4 exhibited excellent sonocatalytic performance.
Article
Full-text available
The presence of a long‐abandoned hexagonal omega (ω) phase in steel samples is recently gaining momentum owing to the advances in transmission electron microscopy (TEM) measurements, even though it is already reported in other transition‐metal alloys. The stabilization of this metastable phase is mainly investigated in presence of C, even though th...
Article
Using density functional theory based simulations, the adsorption of hydrogen on GaN nanowires with [0001] orientation is studied with Pt and Pd functionalization. The adsorption energies show that both Pt and Pd prefer to attach to a top site above the Ga atom in the nanowire. In the pristine GaN, hydrogen attach as a molecule, while in the presen...