Performance evaluation of data embedding schemes for two-dimensional display field communication.

Display field communication (DFC) is an unobtrusive display-to-camera technology that transmits data within the frequency domain of images, ensuring that the embedded data are hidden and do not disrupt the viewing experience. The display embeds data into image frames, while the receiver captures the display and extracts it. Two-dimensional DFC (2D-DFC) focuses on embedding data in the width and height of an image. This study explores two methods to minimize the error rate in 2D-DFC without affecting the quality of the displayed image. The orthogonal method embeds data in the orthogonal direction of an image. On the other hand, the diagonal embedding method strategically embeds the data in the diagonal direction. Experiments show the diagonal method maintains a higher peak signal-to-noise ratio and surpasses the orthogonal embedding method in terms of bit error rate. 2D-DFC is expected to have practical applications in digital signage, advertising and informational displays at airports and train stations, as well as at large-scale displays for events, sports arenas, and performance venues.

Comprehensive analysis of common polymers using hyphenated TGA-FTIR-GC/MS and Raman spectroscopy towards a database for micro- and nanoplastics identification, characterization, and quantitation.

Environmental contamination by micro- and nanoplastics (MNPs) is well documented with potential for their increased accumulation globally. Growing public concern over environmental, ecological, and human exposure to MNPs has led to exponential increase in publications, news articles, and reports (Casillas et al., 2023). Significant knowledge gap exists in standardized analytical methods for the identification and quantification of MNPs from real world environmental samples. Here, we report comprehensive datasets utilizing thermogravimetric analyzer (TGA) coupled to a Fourier transformed infrared spectrometer (FTIR) and a gas chromatography/mass spectrometer (GC/MS) with corresponding Raman spectral data for the most common polymers documented to be present in the environment (35 plastics of 12 polymer types), to serve as a base line reference for the identification and quantitation of MNPs. Various parameters for TGA-FTIR-GC/MS data acquisition were optimized. Commercial consumer plastic product compositions were identified using this analytical database. Case studies to showcase the utility of the method for polymer mixtures analysis is included. This dataset would serve towards the development of a collaborative, global, comprehensive, and curated public database for the identification of various MNPs and mixtures.

CO2 coverage on Pd catalysts accelerates oxygen removal in oxy-combustion systems.

Oxy-combustion systems result in enriched CO2 in exhaust gases; however, the utilization of the concentrated CO2 stream from oxy-combustion is limited by remnant O2. CH4 oxidation using Pd catalysts has been found to have high O2-removal efficiency. Here, the effect of excess CO2 in the feed stream on O2 removal with CH4 oxidation is investigated by combining experimental and theoretical approaches. Experimental results reveal complete CH4 oxidation without any side-products, and a monotonic increase in the rate of CO2 generation with an increase in CO2 concentration in the feed stream. Density-functional theory calculations show that high surface coverage of CO2 on Pd leads to a reduction in the activation energy for the initial dissociation of CH4 into CH3 and H, and also the subsequent oxidation reactions. A CO2-rich environment in oxy-combustion systems is therefore beneficial for the reduction of oxygen in exhaust gases.

Single PEDOT Catalyst Boosts CO2 Photoreduction Efficiency.

Atmospheric pollution demands the development of solar-driven photocatalytic technologies for the conversion of CO2 into a fuel; state-of-the-art cocatalyst systems demonstrate conversion efficiencies currently unattainable by a single catalyst. Here, we upend the status quo demonstrating that the nanofibrillar conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is a record-breaking single catalyst for the photoreduction of CO2 to CO. This high catalytic efficiency stems from a highly conductive nanofibrillar structure that significantly enhances surface area, CO2 adsorption and light absorption. Moreover, the polymer's band gap is optimized via chemical doping/dedoping treatments using hydrochloric acid, ammonia hydroxide, and hydrazine. The hydrazine-treated PEDOT catalyst exhibits 100% CO yield under a stable regime (>10 h) with a maximum rate of CO evolution (3000 µmol gcat -1 h-1) that is 2 orders of magnitude higher than the top performing single catalyst and surpassed only by three other cocatalyst systems. Nanofibrillar PEDOT provides a new direction for designing the next generation of high-efficiency photoreduction catalysts.

One-step aerosol synthesis of a double perovskite oxide (KBaTeBiO6) as a potential catalyst for CO2 photoreduction.

This study presents a comprehensive investigation on the aerosol synthesis of a semiconducting double perovskite oxide with a nominal composition of KBaTeBiO6, which is considered as a potential candidate for CO2 photoreduction. We demonstrate the rapid synthesis of the multispecies compound KBaTeBiO6 with extremely high purity and controllable size through a single-step furnace aerosol reactor (FuAR) process. The formation mechanism of the perovskite through the aerosol route is investigated using thermogravimetric analysis to identify the optimal reference temperature, residence time and other operational parameters in the FuAR synthesis process to obtain highly pure KBaTeBiO6 nanoparticles. It is observed that particle formation in the FuAR is based on a combination of gas-to-particle and liquid-to-particle mechanisms. The phase purity of the perovskite nanoparticles depends on the ratio of the residence time and the reaction time. The particle size is strongly affected by the precursor concentration, residence time and furnace temperature. Finally, the photocatalytic performance of the synthesized KBaTeBiO6 nanoparticles is investigated for CO2 photoreduction under UV-light. The best performing sample exhibits an average CO production rate of 180 µmol g-1 h-1 in the first half hour with a quantum efficiency of 1.19%, demonstrating KBaTeBiO6 as a promising photocatalyst for CO2 photoreduction.

Nitrite reduction mechanism on a Pd surface.

Nitrate (NO3-) is one of the most harmful contaminants in the groundwater, and it causes various health problems. Bimetallic catalysts, usually palladium (Pd) coupled with secondary metallic catalyst, are found to properly treat nitrate-containing wastewaters; however, the selectivity toward N2 production over ammonia (NH3) production still requires further improvement. Because the N2 selectivity is determined at the nitrite (NO2-) reduction step on the Pd surface, which occurs after NO3- is decomposed into NO2- on the secondary metallic catalyst, we here performed density functional theory (DFT) calculations and experiments to investigate the NO2- reduction pathway on the Pd surface activated by hydrogen. Based on extensive DFT calculations on the relative energetics among ∼100 possible intermediates, we found that NO2- is easily reduced to NO* on the Pd surface, followed by either sequential hydrogenation steps to yield NH3 or a decomposition step to N* and O* (an adsorbate on Pd is denoted using an asterisk). Based on the calculated high migration barrier of N*, we further discussed that the direct combination of two N* to yield N2 is kinetically less favorable than the combination of a highly mobile H* with N* to yield NH3. Instead, the reduction of NO2- in the vicinity of the N* can yield N2O* that can be preferentially transformed into N2 via diverse reaction pathways. Our DFT results suggest that enhancing the likelihood of N* encountering NO2- in the solution phase before combination with surface H* is important for maximizing the N2 selectivity. This is further supported by our experiments on NO2- reduction by Pd/TiO2, showing that both a decreased H2 flow rate and an increased NO2- concentration increased the N2 selectivity (78.6-93.6% and 57.8-90.9%, respectively).

Development of Pd-Cu/hematite catalyst for selective nitrate reduction.

A new hematite-supported Pd-Cu bimetallic catalyst (Pd-Cu/hematite) was developed in order to actively and selectively reduce nitrate (NO3(-)) to nitrogen gas (N2). Four different iron-bearing soil minerals (hematite (H), goethite (G), maghemite (M), and lepidocrocite (L)) were transformed to hematite by calcination and used for synthesis of different Pd-Cu/hematite-H, G, M, and L catalysts. Their characteristics were identified using X-ray diffraction (XRD), specific surface area (BET), temperature programed reduction (TPR), transmission electron microscopy with energy dispersive X-ray (TEM-EDX), H2 pulse chemisorption, zeta-potential, and X-ray photoelectron spectroscopy (XPS). Pd-Cu/hematite-H exhibited the highest NO3(-) removal (96.4%) after 90 min, while a lower removal (90.9, 51.1, and 30.5%) was observed in Pd-Cu/hematite-G, M, and L, respectively. The results of TEM-EDX, and TPR analysis revealed that Pd-Cu/hematite-H possessed the closest contact distance between the Cu and Pd sites on the hematite surface among the different Pd-Cu/hematite catalysts. The high removal can be also attributed to the highly active metallic sites on its positively charged surface. The XPS analysis demonstrated that the amount of hydrogen molecules can have a pivotal function on NO3(-) removal and a ratio of nitrogen to hydrogen molecule (N:H) on the Pd sites can critically determine N2 selectivity.