Dr. Branson Belle

Publication/source: ACS Applied Materials & Interfaces 17 (36), 50977, 2025

Snippet: Highly sensitive and energy-efficient gas sensors are essential for real-time environmental monitoring and air quality assessment. In this work, we present an optically programmable gas sensor based on WSe2/hBN heterostructure transistors for NO x detection. The hBN interfacial layer enhances device performance by reducing charge trapping and improving transport, enabling the WSe2/hBN configuration to achieve a higher sensing response and faster recovery than WSe2/SiO2 devices. To understand the sensing mechanism, in situ Kelvin probe force microscopy (KPFM) was used, revealing that NO x adsorption at the metal/semiconductor interface modulates the Schottky barrier height (SBH), which governs charge transport and gas sensitivity. Furthermore, we demonstrate that UV-induced charge modulation allows dynamic control of the sensor response, offering a tunable and reversible method for optimizing gas detection. This study highlights the potential of heterostructure engineering and optoelectronic modulation in developing next-generation, low-power, smart gas sensors for environmental monitoring applications.

Publication/source: ACS Applied Engineering Materials 3 (9), 3022-3033, 2025

Snippet: Hexavalent chromium (Cr6+) based coatings are currently the industry standard for protecting aluminum surfaces from corrosion while improving the corrosion resistance. As hexavalent chromium compounds are known carcinogens and lead to negative impacts in the environment, there is a need to develop safer coatings with comparable performance. In this study, a suite of corrosion and abrasion resistant composite coatings were prepared via the sol–gel method using 3-(aminopropyl)triethoxysilane (APTES), 3-glycidyloxypropyl trimethoxysilane (GPTMS), and phenyltrimethoxysilane (PTMS), which incorporated graphene oxide (GO) and APTES-functionalized graphene oxide (fGO) coated on an aluminum alloy, AA2024-T3. The effect of the ratio of the incorporated materials and the coating thickness on the corrosion resistance as well as the mechanical properties, including hardness, Young’s modulus, and abrasion resistance, of composite coatings was examined. Electrochemical corrosion testing indicated that all of the developed coatings provided over 95% corrosion protection efficiency, while fGO-containing coatings achieved over 99.9% protection efficiency and a nearly 104 times decrease in corrosion current. Furthermore, hardness of the coatings was improved with incorporation of fGO, from 0.25 to 0.61 GPa, which contributed to the observed increase in abrasion resistance. The abrasion strength remained stable in the fGO-containing coatings under the salt spray test, indicating that the fGO-containing coatings maintain their stability even under harsh conditions.

Publication/source: Frontiers in Marine Science 12, 1658207, 2025

Snippet: Ocean carbon sink is an emerging and interdisciplinary research area that plays a vital role in the global carbon cycle. This paper reviews recent scientific advancements in ocean carbon sink research, focusing on the mechanisms for capturing, utilizing, and sequestering atmospheric CO2, and highlights its contribution to climate change mitigation and adaptation. Using bibliometric analysis based on CiteSpace and data from the Web of Science and Scopus, we examine research hotspots and topic evolution through country collaboration, journal co-citation, and keyword co-occurrence networks. The findings show that ocean carbon sink research is shaped by complex scientific uncertainties and the integration of multiple disciplines. Current research hotspots include scientific advances, technological innovation, and governance challenges related to sustainable development. In general, recent studies emphasize the role of carbon sink, the value of nature, and the importance of precautionary management. This paper underlines the need for coordination between scientific and social dimensions of carbon sink functions, and it draws attention to the ethical aspects of carbon sink governance. It advocates for multi-stakeholder participation, precautionary governance, and policy-based financial system to support climate resilience and foster the sustainable development of the oceans.

Publication/source: ACS Applied Nano Materials 7 (11), 12366-12375, 2024

Snippet: We have previously shown that one-dimensional edge contact to two-dimensional heterostructure field effect transistors with a graphene channel, and hexagonal boron nitride, as both the substrate material and top encapsulated layer, show ultrahigh carrier mobility and ultralow carrier noise (low frequency noise, LFN). Although the noise mechanism of the transistor devices in the ON state was modeled based on microscopic scattering mechanisms caused by charge carriers and phonons, the model was based on normalized noise spectral density following Hooge’s noise model in the ON-state. In this article, we show that the normalized noise current densities within the charge residual region of two similarly fabricated edge-contacted and encapsulated graphene heterostructure field effect transistors show different trends with overdrive voltage that resemble previously reported results in the literature. Here we explain the poorly understood and conflicting LFN trends in the charge residual region (low charge carrier regime) by correlating the spatial charge inhomogeneity near the Dirac point in heterostructure devices to electron–hole puddles. By systematically studying the temperature-dependent transport, LFN and by modeling the channel characteristics in such devices within the charge residual region, we show that the carriers inside electron–hole puddles get pinned at lower temperatures and unpinned at higher temperatures, as consistently shown in their normalized flat-band spectral variation as a function of overdrive voltage. More generally, near the charge neutrality region of single-layer graphene devices, the LFN is described by a correlated carrier number and mobility fluctuations of the charge carriers. Understanding the carrier physics in encapsulated high-performance and edge-contacted heterostructure two-dimensional devices will aid us in not only engineering low-noise graphene-based FETs for future digital and analog electronics but also understanding the noise associated with Dirac-type materials.

Publication/source: Small 20 (23), 2307037, 2024

Snippet: This study employs novel growth methodologies and surface sensitization with metal nanoparticles to enhance and manipulate gas sensing behavior of two‐dimensional (2D)SnS film. Growth of SnS films is optimized by varying substrate temperature and laser pulses during pulsed laser deposition (PLD). Thereafter, palladium (Pd), gold (Au), and silver (Ag) nanoparticles are decorated on as‐grown film using gas‐phase synthesis techniques. X‐ray diffraction (XRD), Raman spectroscopy, and Field‐emission scanning electron microscopy (FESEM) elucidate the growth evolution of SnS and the effect of nanoparticle decoration. X‐ray photoelectron spectroscopy (XPS) analyses the chemical state and composition. Pristine SnS, Ag, and Au decorated SnS films are sensitive and selective toward NO2 at room temperature (RT). Ag nanoparticle increases the response of pristine SnS from 48 to 138% toward 2 ppm NO2, which indicates electronic and chemical sensitization effect of Ag. Pd decoration on SnS tunes its selectivity toward H2 gas with a response of 55% toward 70 ppm H2 and limit of detection (LOD) < 1 ppm. In situ Kelvin probe force microscopy (KPFM) maps the work function changes, revealing catalytic effect of Ag toward NO2 in Ag‐decorated SnS and direct charge transfer between Pd and SnS during H2 exposure in Pd‐decorated SnS.