Anton Tadich

Quantum materials that combine magnetism with topological order are emerging as key platforms for next-generation spintronics and low-energy electronics. They enable the realization of emergent quantum phenomena, such as the quantum anomalous Hall effect and axion insulator states. The ferromagnetic insulator (FMI)/topological insulator (TI)/FMI sandwich structure of a single-septuple layer (1SL) MnBi₂Te₄/four-quintuple layer (4QL) Bi₂Te₃/1SL MnBi₂Te₄ holds great potential to achieve such desirable quantum phenomena at an elevated temperature, owing to its large Dirac point band gap and high Curie temperature. Here, spin- and angle-resolved photoemission spectroscopy (spin-ARPES) is employed to directly verify that the band gap arises from broken time-reversal symmetry via proximity-driven magnetization. This study demonstrates direct control of the spin state via external magnetic fields and unambiguously confirms the exchange interaction as the gap-opening mechanism. The robust magnetic gap and controllable spin texture make this heterostructure a suitable candidate for spintronic applications and magnetic topological quantum phases.

Ionically bonded interfaces are crucial for achieving selective and stable direct seawater electrolysis, yet their vulnerability under corrosive and high-current conditions limits long-term performance. Here, we report a two-dimensional Fe-MOF@PW₈O₂₆.B₂O₃ heterostructured electrocatalyst, synthesized via a solid-liquid interfacial growth strategy, that integrates robust Fe-O-W and tunable Fe-P-W ionic bonds to strengthen interfacial electronic coupling, redox flexibility, and structural integrity. Subsurface B₂O₃ enhances surface hydroxylation via Lewis acid-base interactions, facilitating catalyst assembly and OH^- affinity, while phosphate polyanions at the interface act as electrostatic shields that repel Cl^- ions and modulate the redox environment of Fe active sites. This interfacial configuration enables chlorine-suppressive oxygen evolution with a Faradaic efficiency of 97.93%, achieving a current density of 1.75 A cm^-2 at 2.0 V and stable operation above 1.5 A cm^-2 for over 500 h in alkaline seawater, with an exceptionally low corrosion rate of 0.016 μm per year. NEXAFS and XPS analyses confirm the presence of dual ionic linkages, while DFT calculations reveal their cooperative role in stabilizing the electronic structure and interfacial charge distribution. Beyond hydrogen production, the spent electrolyte is repurposed for CO₂ mineralization, achieving 88.76% conversion to stable carbonates, with cytotoxicity assays confirming reduced environmental toxicity. Together, this study establishes a multifunctional ionically engineered platform for durable, chlorine-free seawater electrolysis and integrated carbon capture, advancing the prospects of circular hydrogen systems.

Sulfur radicals are highly reactive intermediates that can greatly accelerate reaction kinetics in lithium-sulfur batteries. However, the intrinsic instability restricts their applications. Herein, we reveal and validate the formation of ultrastable triplet sulfur radical pairs ([S_x·^- - S_x·^-], x = 2, 3, 4) by combining electron paramagnetic resonance and synchrotron radiations. These radical pairs are produced during the spontaneous decomposition of polysulfide molecules on ferrimagnetic surface, where the sulfur radicals adopt parallel spin alignment and pair into stable triplet states through Hund's Rule. These radicals enable exceptionally rapid sulfur conversion, delivering a 100-fold kinetic enhancement compared to the traditional polysulfide molecules. Using these triplet radical pairs, the lithium-sulfur battery achieves a remarkable discharge capacity of 728 mAh g^-1, even at an ultrahigh current rate of 8.0 C, with high sulfur loading and lean electrolyte. Significantly, this is the highest capacity under ultrafast charge-discharge rates reported to date.

Fluorescent nanodiamonds (FNDs) containing nitrogen-vacancy (NV) defects are useful probes for biological imaging and nanoscale sensing applications. Here, we explore the effect of chemical surface modifications and core-shell structures on the T₁ relaxation times of 100 nm FNDs hosting nitrogen-vacancy ensembles. The results show that surface oxidation and silica coating of FNDs using the Stöber method can dramatically increase the spin relaxation time from T₁ = 320 ± 9 μs to T₁ = 1.00 ± 0.06 ms. Using FT-IR and NEXAFS measurements conducted on air oxidized particles, we find that changes to surface functional groups and sp² carbon density may be responsible for the observed enhancements to the spin relaxation rate. Finally, we use a Monte Carlo model to numerically investigate the relationship between chemical sensitivity and shell thickness and find that a shell thickness on the order of 1 nm should provide the highest sensitivity. Our findings demonstrate that the surface of FNDs can be engineered to exhibit bulk-like T₁ relaxation times, in the absence of complex quantum control sequences, which is crucial to advancing biosensing and imaging applications where surface spin noise currently limits measurement precision.

Hydrogen production from seawater is promising; however, the complex chemistry and corrosive nature of seawater are a huge bottleneck. Therefore, it is imperative to design catalysts that provide highly active and stable catalytic sites for preferential seawater catalysis. Here, we constructed an interface by heterostructuring boron-doped iron disulfide (B-FeS₂) sheets with metal-organic framework (MOF) sheets to achieve higher activity and longer life, confirmed through theoretical and experimental results. B facilitates Ni-S ionic interactions at the heterointerface with a 2.28 Å bond length, which modulates the electronic properties and the surface chemistry. It also yields borate species at the interface, which act as a local OH^- modulator and favor OH^- adsorption. The presence of SO₄^2- ions on the surface works as a repellent to corrosive Cl^- ions. As a result, the heterostructure achieves an anodic current density of 1.5 A/cm² at an overpotential of 628 mV without chlorine-related reaction and remains stable for over 500 h in seawater. Antichlorine and anticorrosion tests further reveal that the catalyst is highly stable and strongly inhibits chlorine chemistry, further supported by theoretical calculations and ex situ materials analysis. Hence, an ideal pathway to realize H₂ production directly from seawater via materials engineering is presented.

Ammonia has recently attracted growing attention as a promising hydrogen carrier because it can be liquefied and stored in bulk under mild conditions. To fully harness its potential, more efforts are needed to elucidate and control the mechanisms of its decomposition. Here we show that intermediate dimerization processes proceed through a cooperative spin alignment effect between intermediates and can be promoted by the magnetic ordering rearrangement of magnetic substrates. We explored a series of Co/Pt magnetic thin-film catalysts as model materials to investigate spin-sensitive NH_x dimerization and eventual enhancement on catalytic activity. Through in situ spectroscopic analysis and theoretical verification, we demonstrate that coupling of N–NH with aligned net magnetic moments is the most favourable with the lowest energy barriers. This provides a precedent for understanding spin kinetics to help improve the catalytic efficiency of electrochemical ammonia decomposition.

High-entropy oxides (HEOs) offer exceptional compositional flexibility and structural stability, making them promising materials for energy and catalytic applications. Here, we investigate Sr doping effects on B-site cation oxidation states, local composition, and structure in epitaxial La_1-xSr_x(Cr_0.2Mn_0.2Fe_0.2Co_0.2Ni_0.2)O₃ thin films. X-ray spectroscopies reveal that Sr doping preferentially promotes Cr oxidation from Cr³⁺ to Cr⁶⁺, partially oxidizes Co and Ni, while leaving Mn⁴⁺ and Fe³⁺ unchanged. Atomic-resolution scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy shows pronounced Cr segregation, with depletion at the interface and enrichment at the surface, along with partial amorphization in heavily Sr-doped samples. This segregation is likely driven by oxidation-induced migration of smaller, high-valence Cr cations during growth. These findings highlight the critical interplay between charge compensation, local strain, and compositional fluctuations in HEOs, indicating that precise control over growth conditions is critical for tuning their surface composition and electronic structure toward more robust electrocatalyst design.

The naturally self‐limiting oxide formed on the surface of liquid metals can be exfoliated and transferred onto various substrates. This oxide layer with a thickness of a few nanometers is typically highly transparent and can be engineered for applications in large‐area optoelectronics. While the incorporation of solvated elements into the interfacial oxide of post‐transition metal‐based liquid metals is demonstrated for n‐doping, achieving p‐doping in such ultrathin oxide layers remains a significant challenge. In this study, the use of dissolved indium (In), platinum (Pt), gold (Au), palladium (Pd), and copper (Cu) in gallium (Ga)‐based alloys is investigated to create a high‐entropy liquid metal system. This allows the exfoliation of a p‐doped ultrathin oxide layer, predominantly composed of gallium oxide (Ga₂O₃). The incorporation of these post‐transition metals in this high‐entropy system results in their atomic dispersion, with Cu exhibiting limited surface presence. The atomically dispersed Pt, Au, and Pd metals scavenge oxygen during exfoliation at moderate temperatures and release them during cooling down, promoting the emergence of trivalent metallic In in Ga oxide layer. This work presents a novel doping strategy at moderate temperatures to achieve p‐doped liquid‐metal‐derived ultrathin Ga₂O₃ layers, which maintain high transparency.