Scanning Transmission Electron Microscopy Images Research Articles

DFT-Assisted Investigation of the Electric Field and Charge Density Distribution of Pristine and Defective 2D WSe2 by Differential Phase Contrast Imaging.

Most properties of solid materials are defined by their internal electric field and charge density distributions which so far are difficult to measure with high spatial resolution. Especially for 2D materials, the atomic electric fields influence the optoelectronic properties. In this study, the atomic-scale electric field and charge density distribution of WSe2 bi- and trilayers are revealed using an emerging microscopy technique, differential phase contrast (DPC) imaging in scanning transmission electron microscopy (STEM). For pristine material, a higher positive charge density located at the selenium atomic columns compared to the tungsten atomic columns is obtained and tentatively explained by a coherent scattering effect. Furthermore, the change in the electric field distribution induced by a missing selenium atomic column is investigated. A characteristic electric field distribution in the vicinity of the defect with locally reduced magnitudes compared to the pristine lattice is observed. This effect is accompanied by a considerable inward relaxation of the surrounding lattice, which according to first principles DFT calculation is fully compatible with a missing column of Se atoms. This shows that DPC imaging, as an electric field sensitive technique, provides additional and remarkable information to the otherwise only structural analysis obtained with conventional STEM imaging.

Disruption of polar order in lead zirconate titanate by composition-modulated artificial superlattice

AbstractLead zirconate titanate (Pb (Zrx, Ti1−x)O3: PZT) is a well-known ferroelectric compound, in which long-range polar order is usually developed. In the present study, it was clarified by distortion-corrected atomic-scale scanning transmission electron microscopy imaging that long-range polar order is disrupted in PZT by utilizing composition-modulated superlattice. Shape of unit cell was unusual both in the Pb(Zr0.65Ti0.35)O3 (PZT65) and Pb(Zr0.30Ti0.70)O3 (PZT30) layers, which was due to mutual in-plane lattice constraint. By taking account of this, first-principles calculations clarified that multiple directions can be energetically favorable for lead-ion displacement, which explains a reason why long-range polar order was disrupted.

An advanced fast method for the evaluation of multiple immunolabelling using gold nanoparticles based on low-energy STEM

We present a powerful method for the simultaneous detection of Au nanoparticles located on both sides of ultrathin sections. The method employs a high-resolution scanning electron microscope (HRSEM) operating in scanning transmission electron microscopy (STEM) mode in combination with the detection of backscattered electrons (BSE). The images are recorded simultaneously during STEM and BSE imaging at the precisely selected accelerating voltage. Under proper imaging conditions, the positions of Au nanoparticles on the top or bottom sides can be clearly differentiated, hence showing this method to be suitable for multiple immunolabelling using Au nanoparticles (NPs) as markers. The difference between the upper and lower Au NPs is so large that it is possible to apply common software tools (such as ImageJ) to enable their automatic differentiation. The effects of the section thickness, detector settings and accelerating voltage on the resulting image are shown. Our experimental results correspond to the results modelled in silico by Monte Carlo (MC) simulations.

Oxidation behavior and atomic structural transition of size-selected coalescence-resistant tantalum nanoclusters.

Herein a series of size-selected TaN (N=147, 309, 561, 923, 1415, 2057, 6525, 10000, 20000) clusters are generated using a gas-phase condensation cluster beam source equipped with a lateral time-of-flight (TOF) mass-selector. Aberration-corrected scanning transmission electron microscopy (AC-STEM) imaging reveals good thermal stability of TaN clusters in this study. The oxidation-induced amorphization is observed from AC-STEM imaging and further demonstrated through X-ray photoelectron spectroscopy (XPS) and energy-dispersive spectroscopy (EDS). The oxidized Ta predominantly exists in the +5 oxidation state and the maximum spontaneous oxidation depth of Ta cluster is observed to be 5 nm under prolonged atmosphere exposure. Furthermore, the size-dependent sintering and crystallization process of oxidized TaN clusters is observed with in-situ heating technique, and eventually, ordered structures are restored. As temperature reaches 1300 °C, a fraction of oxidized Ta309 clusters exhibit decahedral and icosahedral structures, but the five-fold symmetry structures are absent in larger clusters, instead, these clusters exhibit ordered structures resembling those of the crystalline Ta2O5 films. Notably, the sintering and crystallization process occurs at temperatures significantly lower than the melting point of Ta and Ta2O5, and the ordered structures resulting from annealing remain well-preserved after six months of exposure to ambient condition.&#xD.

Tuning grain boundary cation segregation with oxygen deficiency and atomic structure in a perovskite compositionally complex oxide thin film

Compositionally complex oxides (CCOs) are an emerging class of materials encompassing high entropy and entropy stabilized oxides. These promising advanced materials leverage tunable chemical bond structure, lattice distortion, and chemical disorder for unprecedented properties. Grain boundary (GB) and point defect segregation to GBs are relatively understudied in CCOs even though they can govern macroscopic material properties. For example, GB segregation can govern local chemical (dis)order and point defect distribution, playing a critical role in electrochemical reaction kinetics, and charge and mass transport in solid electrolytes. However, compared with conventional oxides, GBs in multi-cation CCO systems are expected to exhibit more complex segregation phenomena and, thus, prove more difficult to tune through GB design strategies. Here, GB segregation was studied in a model perovskite CCO LaFe0.7Ni0.1Co0.1Cu0.05Pd0.05O3−x textured thin film by (sub-)atomic-resolution scanning transmission electron microscopy imaging and spectroscopy. It is found that GB segregation is correlated with cation reducibility—predicted by an Ellingham diagram—as Pd and Cu segregate to GBs rich in oxygen vacancies (VO··). Furthermore, Pd and Cu segregation is highly sensitive to the concentration and spatial distribution of VO·· along the GB plane, as well as fluctuations in atomic structure and elastic strain induced by GB local disorder, such as dislocations. This work offers a perspective of controlling segregation concentration of CCO cations to GBs by tuning reducibility of CCO cations and oxygen deficiency, which is expected to guide GB design in CCOs.

Using convolutional neural networks for stereological characterization of 3D hetero-aggregates based on synthetic STEM data

The 3D nano/microstructure of materials can significantly influence their macroscopic properties. In order to enable a better understanding of such structure-property relationships, 3D microscopy techniques can be deployed, which are however often expensive in both time and costs. Often 2D imaging techniques are more accessible, yet they have the disadvantage that the 3D nano/microstructure of materials cannot be directly retrieved from such measurements. The motivation of this work is to overcome the issues of characterizing 3D structures from 2D measurements for hetero-aggregate materials. For this purpose, a method is presented that relies on machine learning combined with methods of spatial stochastic modeling for characterizing the 3D nano/microstructure of materials from 2D data. More precisely, a stochastic model is utilized for the generation of synthetic training data. This kind of training data has the advantage that time-consuming experiments for the synthesis of differently structured materials followed by their 3D imaging can be avoided. More precisely, a parametric stochastic 3D model is presented, from which a wide spectrum of virtual hetero-aggregates can be generated. Additionally, the virtual structures are passed to a physics-based simulation tool in order to generate virtual scanning transmission electron microscopy (STEM) images. The preset parameters of the 3D model together with the simulated STEM images serve as a database for the training of convolutional neural networks, which can be used to determine the parameters of the underlying 3D model and, consequently, to predict 3D structures of hetero-aggregates from 2D STEM images. Furthermore, an error analysis is performed with respect to structural descriptors, e.g. the hetero-coordination number. The proposed method is applied to image data of TiO2-WO3 hetero-aggregates, which are highly relevant in photocatalysis processes. However, the proposed method can be transferred to other types of aggregates and to different 2D microscopy techniques. Consequently, the method is relevant for industrial or laboratory setups in which product quality is to be quantified by means of inexpensive 2D image acquisition.

In-situ construction of porous carbon substrate from sodium carboxymethyl cellulose boosting ultra-long lifespan for Na3V2(PO4)3 cathode material

Na3V2(PO4)3 (trisodium divanadium (III) tris (orthophosphate [NVP]), the cathode material for sodium ion batteries, faces several challenges, such as lower intrinsic electronic and ionic conductivities, which hinder its commercial viability. In this work, NVP system is modified by introducing sodium carboxymethyl cellulose (Na CMC) to achieve triple modification effects: sodium-rich, cross-linked carbon coating network, and carbon layer surface modification. Meanwhile, CMC, as a porous carbon substrate with large pores, provides a fast migration channel for Na+. Similarly, carbon nanotubes (CNTs) grown from the active particles become the connecting carriers between the active particles, thus effectively improving the electron transport. Notably, the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images after cycling verify the stabilized porous structure of the Na3V2(PO4)3/C@0.7wt.%CMC@CNTs (0.7wt.%CMC@CNTs) composite. Distinctively, the modified 0.7wt.%CMC@CNTs reveals a capacity of 111.4 mAh/g at 0.1 C. It submits a high value of 105.0 mAh/g at 1 C with a capacity retention rate of 84.10% after 1,000 cycles. Even at 15 C, it still releases 86.6 mAh/g with a low capacity decay rate of 0.0230% per cycle after 3,600 cycles. Notably, its capacity retention reaches an astonishing 96.09% after 13,000 cycles at an ultra-high rate of 80 C.

Nano-scale corrosion mechanism of T91 steel in static lead-bismuth eutectic: A combined APT, EBSD, and STEM investigation

T91 steel is a candidate material for structural components in lead-bismuth-eutectic (LBE) cooled systems, for example fast reactors and solar power plants [1]. However, the corrosion mechanisms of T91 in LBE remain poorly understood. In this study, we have analysed the static corrosion of T91 in liquid LBE using a range of characterisation techniques at increasingly smaller scales. A unique pattern of liquid metal intrusion was observed that does not appear to correlate with the grain boundary network. Upon closer inspection, electron backscatter diffraction (EBSD) reveals a change in the morphology of grains at the LBE-exposed surface, suggesting a local phase transition. Energy dispersive X-ray (EDX) maps show that Cr is depleted in the T91 material near the LBE interface. Furthermore, we observed the dissolution of all Cr-enriched precipitates in this region. Although the corrosion is conducted in an oxygen deficient environment, both scanning transmission electron microscopy (STEM) and atom probe tomography (APT) reveal a thin surface oxide layer (presumably wüstite) at the LBE-steel interface. Using electron energy loss spectroscopy (EELS) in the STEM, as well as APT, the atomic scale elemental redistribution and 3D morphology of the corrosion interface is investigated. By combining results from these different techniques, several types of oxide phases and structures can be identified. Based on this detailed nano-scale information, we propose potential mechanisms of T91 corrosion in LBE.

Epitaxial growth of α-(AlxGa1−x)2O3 by suboxide molecular-beam epitaxy at 1 µm/h

We report the use of suboxide molecular-beam epitaxy (S-MBE) to grow α-(AlxGa1−x)2O3 films on (110) sapphire substrates over the 0 < x < 0.95 range of aluminum content. In S-MBE, 99.98% of the gallium-containing molecular beam arrives at the substrate in a preoxidized form as gallium suboxide (Ga2O). This bypasses the rate-limiting step of conventional MBE for the growth of gallium oxide (Ga2O3) from a gallium molecular beam and allows us to grow fully epitaxial α-(AlxGa1−x)2O3 films at growth rates exceeding 1 µm/h and relatively low substrate temperature (Tsub = 605 ± 15 °C). The ability to grow α-(AlxGa1−x)2O3 over the nominally full composition range is confirmed by Vegard’s law applied to the x-ray diffraction data and by optical bandgap measurements with ultraviolet–visible spectroscopy. We show that S-MBE allows straightforward composition control and bandgap selection for α-(AlxGa1−x)2O3 films as the aluminum incorporation x in the film is linear with the relative flux ratio of aluminum to Ga2O. The films are characterized by atomic-force microscopy, x-ray diffraction, and scanning transmission electron microscopy (STEM). These α-(AlxGa1−x)2O3 films grown by S-MBE at record growth rates exhibit a rocking curve full width at half maximum of ≊ 12 arc secs, rms roughness <1 nm, and are fully commensurate for x ≥ 0.5 for 20–50 nm thick films. STEM imaging of the x = 0.78 sample reveals high structural quality and uniform composition. Despite the high structural quality of the films, our attempts at doping with silicon result in highly insulating films.

Natural resource-derived NiO nanoparticles via aloe vera for high-performance symmetric supercapacitor

This investigation reported a one-step green synthesis of nickel oxide nanoparticles (NiO NPs) using aloe vera leaves extract solution for their application in a supercapacitor. This method used aloe vera leaves as a reducing agent, which is very simple and cost-effective. The synthesized NPs were thoroughly characterized using various techniques. The X-ray diffraction analysis unequivocally confirmed the crystalline nature; field emission scanning electron microscopy and transmission electron microscopy images showed different shapes and forms of an agglomerated cluster of synthesized NPs. The absorption spectra were recorded from UV visible spectroscopy, while Fourier transform infrared spectroscopy provided insights into the functional groups present. Electrochemical assessments were carried out via cyclic voltammetry, galvanostatic charging-discharging and electrochemical impedance spectroscopy. These experiments were performed using a 2 M KOH electrolyte within a 1.0 V potential window. Impressively, the single electrode displayed a remarkable specific capacitance of 462 F g−1 at a scan rate of 1 mV s−1 and 336 F g−1 at a current density of 0.76 A g−1. Further, a symmetric two-electrode device (NiO||NiO) has been successfully fabricated by employing a separator between the electrodes. The device exhibited an exceptional specific capacitance of approximately 239 F g−1, along with an energy density of 47.8 Wh kg−1 and a power density of 545 W kg−1 at 1 A g−1 current density within a 1.2 V potential window. The fabricated device also shows a retention capacity of 89% at 10 A g−1 after 2000 cycles with 114% of columbic efficiency. The present study underscores the effectiveness of the green synthesis approach in producing NiO NPs and establishes their potential as highly promising candidates for supercapacitor applications, showcasing both excellent electrochemical performance in a three-electrode system and remarkable stability in a practical two-electrode device. The results collectively highlight the efficacy of the green approach in producing NiO NPs, establishing its potential as a highly promising candidate for supercapacitor application.

Al-Cu intermetallic phase growth in hybrid metal extrusion & bonding welds exposed to isothermal annealing or direct current cycling

Joining of aluminium (Al) to copper (Cu) is of great interest to power generation, transportation and electronic industry. However, dissimilar metal joining often promotes intermetallic phase formation at the joined interface, which in redundancy can cause mechanical degradation and increased electrical resistance. The welding technique hybrid metal extrusion & bonding (HYB) is proven capable of joining dissimilar metals with a total intermetallic phase layer thickness <▪. To test how Al-Cu HYB joints perform as electrical conductors, a 6101 Al alloy HYB-welded to Cu is exposed to heat treatment at ▪ or cycling of direct current density up to ▪. In-depth micro- and nanostructure characterisation by (scanning) transmission electron microscopy and atom probe tomography are used to describe the structure and chemistry of the formed intermetallic phases.The Al-Cu HYB joints exhibited resilience against intermetallic phase growth during isothermal heat treatment or exposure to electric current. However, a non-symmetry is observed dependent on the current direction, creating voids in Cu near, and in the intermetallic layers when the current goes from Al to Cu. Detailed microstructure characterisation unveils Si and Mg in the intermetallic phase layers. Their origin and role in intermetallic phase growth are discussed.

Characterization of Mn5Ge3 Contacts on a Shallow Ge/SiGe Heterostructure.

Mn5Ge3 is a ferromagnetic phase of the Mn-Ge system that is a potential contact material for efficient spin injection and detection. Here, we investigate the creation of Mn5Ge3-based contacts on a Ge/SiGe quantum well heterostructure via solid-state synthesis. X-ray diffraction spectra fitting indicates the formation of Mn5Ge3-based contacts on bulk Ge and Ge/SiGe. High-resolution scanning transmission electron microscopy imaging and energy dispersive X-ray spectroscopy verify the correct Mn5Ge3-based phase formation. Schottky diode measurements, transmission line measurements, and Hall measurements reveal that Mn5Ge3-based contacts serve as good p-type contacts for Ge/SiGe quantum well heterostructures due to having a low Schottky barrier height of 0.10eV (extracted from a Mn5Ge3/n-Ge analogue) and a contact resistance in the order of 1 kΩ. Furthermore, we show that these electrical characteristics have a gate-voltage dependence, thereby providing tunability.

Vertically Stacked Amorphous Ir/Ru/Ir Oxide Nanosheets for Boosted Acidic Water Splitting.

Integrating multiple functional components into vertically stacked heterostructures offers a prospective approach to manipulating the physicochemical properties of materials. The synthesis of vertically stacked heterogeneous noble metal oxides remains a challenge. Herein, we report a surface segregation approach to create vertically stacked amorphous Ir/Ru/Ir oxide nanosheets (NSs). Cross-sectional high-angle annular darkfield scanning transmission electron microscopy images demonstrate a three-layer heterostructure in the amorphous Ir/Ru/Ir oxide NSs, with IrOx layers located on the upper and lower surfaces, and a layer of RuOx sandwiched between the two IrOx layers. The vertically stacked heterostructure is a result of the diffusion of Ir atoms from the amorphous IrRuOx solid solution to the surface. The obtained A-Ir/Ru/Ir oxide NSs display an ultralow overpotential of 191 mV at 10 mA cm-2 toward acid oxygen evolution reaction and demonstrate excellent performance in a proton exchange membrane water electrolyzer, which requires only 1.63 V to achieve 1 A cm-2 at 60 °C, with virtually no activity decay observed after a 1300 h test.

Atomic structure of clusters and GP-zones in an Al-Mg-Si alloy

The structures of atomic clusters and GP-zones preceding precipitation in an Al-0.70Mg-0.85Si-0.15Fe-0.25Mn (wt. %) alloy have been investigated by annular dark field scanning transmission electron microscopy imaging and density functional theory calculations. One analysed condition consisted of one-month natural aging, and another was in a pre-baked state after 24 h aging at 90 °C. To quantify the effect of clusters and GP-zones on microstructure development during a subsequent isothermal artificial aging at 185 °C, hardness evolution was measured, and precipitate statistics was performed at the peak hardness corresponding to 5 h aging. Several types of clusters and GP-zones have been observed and based on structure and visual appearance named 'Disordered Frank-Kasper', 'Square', 'Binocular', and 1β", 2β", 3β", 4β". The first four are most common in the natural aged condition and are associated with a well-known influence on the initial hardness evolution. The last three are fractions of the hardening β" phase and refer to the number of structural units they contain. These GP-zones have an increased density in the pre-baked condition, leading to a rapid increase in hardness during artificial aging and to a finer microstructure of high-density small needle precipitates at peak hardness.

Quantifying the thickness of WTe2 using atomic-resolution STEM simulations and supervised machine learning.

For two-dimensional (2D) materials, the exact thickness of the material often dictates its physical and chemical properties. The 2D quantum material WTe2 possesses properties that vary significantly from a single layer to multiple layers, yet it has a complicated crystal structure that makes it difficult to differentiate thicknesses in atomic-resolution images. Furthermore, its air sensitivity and susceptibility to electron beam-induced damage heighten the need for direct ways to determine the thickness and atomic structure without acquiring multiple measurements or transferring samples in ambient atmosphere. Here, we demonstrate a new method to identify the thickness up to ten van der Waals layers in Td-WTe2 using atomic-resolution high-angle annular dark-field scanning transmission electron microscopy image simulation. Our approach is based on analyzing the intensity line profiles of overlapping atomic columns and building a standard neural network model from the line profile features. We observe that it is possible to clearly distinguish between even and odd thicknesses (up to seven layers), without using machine learning, by comparing the deconvoluted peak intensity ratios or the area ratios. The standard neural network model trained on the line profile features allows thicknesses to be distinguished up to ten layers and exhibits an accuracy of up to 94% in the presence of Gaussian and Poisson noise. This method efficiently quantifies thicknesses in Td-WTe2, can be extended to related 2D materials, and provides a pathway to characterize precise atomic structures, including local thickness variations and atomic defects, for few-layer 2D materials with overlapping atomic column positions.

Scanning transmission electron microscopy and atom probe tomography analysis of non-stoichiometry long-period-stacking-ordered structures in Mg-Ni-Y/Sm alloys

The long-period-stacking-ordered (LPSO) structure affects the mechanical, corrosion and hydrolysis properties of Mg alloys. The current work employs high angle annular dark field - scanning transmission electron microscopy (HAADF-STEM) and atom probe tomography (APT) to investigate the structural and local chemical information of LPSO phases formed in Mg-Ni-Y/Sm ternary alloys after extended isothermal annealing. Depending on the alloying elements and their concentrations, Mg-Ni-Y/Sm develops a two-phase LPSO + α-Mg structure in which the LPSO phase contains defects, hybrid LPSO structure, and Mg insertions. HAADF-STEM and APT indicate non-stoichiometric LPSO with incomplete Ni6(Y/Sm)8 clusters. In addition, the APT quantitatively determines the local composition of LPSO and confirms the presence of Ni within the Mg bonding layers. These results provide insight into a better understanding of the structure and hydrolysis properties of LPSO-Mg alloys.

Growth mechanism of star-shaped Au–Ag nanoparticles synthesized by ascorbic acid reduction and underpotential deposition

The growth mechanism of star-shaped Au–Ag nanoparticles, which is important for improving the absorption efficiency of nanoparticles in the near-infrared region, remains to be clarified. In this study, the growth mechanism by stabilizing certain facets of Au in spines by underpotential deposition of Ag was investigated. The nanoparticles were analyzed primarily by scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy. Analysis of spines on nanoparticles synthesized with an Au/Ag ratio of 18/4 revealed that approximately 1 nm of Ag was deposited on the topmost surface of Au, and the growth direction of spines was <200>. Underpotential deposition of Ag nanolayers on specific facets of the spines on nanoparticles was observed for the first time by elemental mapping and high-angle annular dark-field STEM tomography. These findings are expected to contribute to the morphology control of plasmonic nanoparticles.

Surface Oxidation of GaN(0001) Simulated by Charge‐Transfer‐Type Molecular Dynamics

In this study, the oxidation of Ga–polar GaN(0001) surface simulated by using originally developed charge‐transfer‐type interatomic potential is reported on. The adjusted potential parameters reproduce the cohesive energies in the range of 0.3 eV atom−1 and atomic forces with correlation coefficient as high as 0.9, compared to the results of first‐principles calculations for more than 9000 structures associated with oxidation of GaN. The oxidation simulations reveal the formation of a periodic gallium oxide (GaOx) layer grown on GaN(0001) with O atoms replacing N atoms. The atomic distance between Ga–Ga in the GaOx layer along GaN[0001] direction is 3.05 Å, which is longer than wurtzite GaN (2.63 Å) and is quantitatively in agreement with the recent photoelectron holography measurement. The distances of the Ga atoms projected onto the GaN(11–20) plane are determined to be 3.19 Å for the GaOx layer and 2.79 Å for the interfacial GaN. These distances also align quantitatively with the scanning transmission electron microscopy imaging of the native oxide on GaN(0001). Further oxidation simulation in a larger model of 2304 atoms suggests the formation of the layered structure even in the subsequent layers away from the interface of GaN and gallium oxide.

Structure and Charge Carrier Separation Promotion Effects of Antiphase Boundaries in Cesium Lead Bromide.

Defects in lead halide perovskites (LHPs) may have a significant impact on charge carrier separation, but the roles of the defects are not fully understood. Here, using aberration-corrected scanning transmission electron microscopy (STEM), different types of antiphase boundaries (APBs) are discovered in CsPbBr3 platelets. APBs with a displacement vector of 1/4[111] are characterized by double layers of CsBr layers at the (110) or (001) planes, while APBs at the (112) planes are formed through edge sharing of PbBr6 ̵octahedra. Significant lattice distortions are determined at (001) and (110) APBs on the basis of quantitative analyses of STEM images. Density functional theory calculations demonstrate that all three types of APBs can induce band offsets at their valence bands and conduction bands. The APBs are intended to promote the separation of photogenerated charge carriers in LHPs. These findings provide a crystal engineering technique for enhancing the optoelectronic properties of LHPs by controlling defects.

Spontaneous Deposition of Single Platinum Atoms on Anatase TiO2 for Photocatalytic H2 Evolution.

Single-atom (SA) decoration has emerged as a frontier in catalysis due to its unique characteristics. Recently, decorated Pt single atoms on titania have shown promise in photocatalytic hydrogen evolution. In this work, we demonstrate that Pt SAs can spontaneously deposit on the surface, driven by electrostatic forces; the key is to determine the golden pH and surface potential. We conducted a comprehensive investigation into the influence of the pH of the deposition precursor on the spontaneous adsorption of Pt SAs onto TiO2 nanosheets (TiNSs). We introduced a straightforward pH-dependent and charge-dependent strategy for the solid electrostatic anchoring of Pt SAs on TiO2. Furthermore, we established that the level of Pt loading can be controlled by adjusting the precursor pH. X-ray photoelectron spectroscopy (XPS) and high-angle annular dark-field imaging scanning transmission electron microscopy (HAADF-STEM) were used to evaluate the Pt SA-decorated samples. Photocatalytic hydrogen production activity was assessed under ultraviolet (UV) (365 nm) irradiation. Notably, we found that at a pH of 8, slightly below the measured point of zero charge (PZC), a unique mixture of Pt clusters and single atoms was deposited on the surface of TiNSs. This unique composition significantly improved hydrogen production, resulting in ∼3.7 mL of hydrogen generated after 8 h of UV exposure by only 10 mg of the Pt-decorated TiNS (with Pt loadings of 0.12 at. %), which is ∼300 times higher than the undecorated TiNS.