Hydrogen sulfide removal is a long-standing economic and environmental challenge faced by the oil and gas industries. H2S separation processes using reactive and non-reactive absorption and adsorption, membranes, and cryogenic distillation are reviewed. A detailed discussion is presented on new developments in adsorbents, such as ionic liquids, metal oxides, metals, metal–organic frameworks, zeolites, carbon-based materials, and composite materials; and membrane technologies for H2S removal. This Review attempts to exhaustively compile the existing literature on sour gas sweetening and to identify promising areas for future developments in the field.

https://pubs.acs.org/doi/pdf/10.1021/acs.chemrev.7b00768

Hydrogen Sulfide Capture: From Absorption in Polar Liquids to Oxide, Zeolite, and Metal-Organic Framework Adsorbents and Membranes.

Wide band gap semiconductors are essential for today's electronic devices and energy applications because of their high optical transparency, controllable carrier concentration, and tunable electrical conductivity. The most intensively investigated wide band gap semiconductors are transparent conductive oxides (TCOs), such as tin-doped indium oxide (ITO) and amorphous In-Ga-Zn-O (IGZO), used in displays and solar cells, carbides (e.g., SiC) and nitrides (e.g., GaN) used in power electronics, and emerging halides (e.g., γ-CuI) and 2D electronic materials (e.g., graphene) used in various optoelectronic devices. Compared to these prominent materials families, chalcogen-based (Ch = S, Se, Te) wide band gap semiconductors are less heavily investigated but stand out because of their propensity for p-type doping, high mobilities, high valence band positions (i.e., low ionization potentials), and broad applications in electronic devices such as CdTe solar cells. This manuscript provides a review of wide band gap chalcogenide semiconductors. First, we outline general materials design parameters of high performing transparent semiconductors, as well as the theoretical and experimental underpinnings of the corresponding research methods. We proceed to summarize progress in wide band gap (EG > 2 eV) chalcogenide materials-namely, II-VI MCh binaries, CuMCh2 chalcopyrites, Cu3MCh4 sulvanites, mixed-anion layered CuMCh(O,F), and 2D materials-and discuss computational predictions of potential new candidates in this family, highlighting their optical and electrical properties. We finally review applications-for example, photovoltaic and photoelectrochemical solar cells, transistors, and light emitting diodes-that employ wide band gap chalcogenides as either an active or passive layer. By examining, categorizing, and discussing prospective directions in wide band gap chalcogenides, this Review aims to inspire continued research on this emerging class of transparent semiconductors and thereby enable future innovations for optoelectronic devices.

https://escholarship.org/content/qt1xf1k15d/qt1xf1k15d.pdf?t=qof0vs

Wide Band Gap Chalcogenide Semiconductors.

DOI: 10.1002/aenm.201301565 The increasing demand for environmentally friendly industries and effective pollution control has attracted great attention from both academic and industrial organizations for the development of new processes and novel materials. As a major air pollutant, hydrogen sulfi de (H 2 S), originating from various sources (natural gas processing, the refi ning and consumption of fossil fuel, etc.) must urgently be removed and reused due to its high toxicity towards the environment (acid rain) and living organisms. [ 1 ] Great efforts have been made to explore the effective removal of H 2 S and in most cases transitionmetal oxides and mixed oxides are used as adsorbents and/or catalysts for the oxidation of H 2 S, whereas others use zeolite, activated carbon (AC), and carbon nanotubes (CNTs) as adsorbents. [ 2,3 ] Carbon materials have appealing properties as adsorbents or catalyst supports for the removal of H 2 S. For instance, AC or CNTs have been widely used as supports of catalysts (ZnO, NiS 2 , etc.) for the catalytic oxidation of H 2 S. [ 3 ] Nevertheless, the regeneration and full utilization of the H 2 S and the development of high-performance adsorbents are still hard to realize. Thus, it is necessary to develop an appropriate approach to eliminate and recycle H 2 S to realize its regeneration and environmental protection. As a fascinating carbon material, graphene possesses excellent electrical, thermal, and mechanical properties due to its unique 2D structure, making it versatile in fundamental science and various applications, such as energy storage, sensors, adsorption, etc. [ 4 ] Due to its large and fully accessible surface and excellent conductivity, the use of graphene in the removal of H 2 S has been examined both experimentally and theoretically. [ 1a, 2, 5 ] Density functional theory (DFT) studies show that H 2 S molecules are physisorbed only on the surface of graphene, thus, in most cases, graphene has a low catalytic activity for H 2 S oxidation and also a low adsorption capacity. Graphene oxide (GO), the most important derivative of graphene, is decorated by abundant oxygen-containing groups on the graphene layer, and these help improve the reactivity and processability due to their hydrophilic nature. Although GO suffers from poor conductivity due to the destruction of the continuous sp 2

Reduction of Graphene Oxide by Hydrogen Sulfide: A Promising Strategy for Pollutant Control and as an Electrode for Li‐S Batteries

Identification of gas molecules plays a key role a wide range of applications extending from healthcare to security. However, the most widely used gas nano-sensors are based on electrical approaches or refractive index sensing, which typically are unable to identify molecular species. Here, we report label-free identification of gas molecules SO2, NO2, N2O, and NO by detecting their rotational-vibrational modes using graphene plasmon. The detected signal corresponds to a gas molecule layer adsorbed on the graphene surface with a concentration of 800 zeptomole per μm2, which is made possible by the strong field confinement of graphene plasmons and high physisorption of gas molecules on the graphene nanoribbons. We further demonstrate a fast response time (<1 min) of our devices, which enables real-time monitoring of gaseous chemical reactions. The demonstration and understanding of gas molecule identification using graphene plasmonic nanostructures open the door to various emerging applications, including in-breath diagnostics and monitoring of volatile organic compounds. Identification of gas molecules is crucial in healthcare and security applications. Here the authors achieve label-free identification of SO2, NO2, N2O, and NO gas molecules by detecting their rotational-vibrational modes using graphene nanoribbon plasmons.

/pdf/gas-identification-with-graphene-plasmons-3dqg82lpse.pdf

Gas identification with graphene plasmons

The thermoelectric properties of pristine graphene and H2S adsorbed onto bridge, hollow and top sites of a graphene sheet are investigated using the semi-classical Boltzmann transport theory. The average values of electrical conductivity, thermal conductivity, Seebeck coefficient, figure of merit (ZT) and the average value of the power factor (Pav) are reported and discussed in detail. While pristine graphene is a zero band gap semiconductor, adsorption of H2S onto the bridge site opens up a direct energy gap of about 0.04 eV, adsorption of a H2S molecule onto the top site opens up a gap of 0.3 eV, and adsorption of H2S onto the hollow site makes it metallic. The investigation of ZT and power factor values suggests that a top-site configuration could be a potential candidate for thermoelectric applications in the range 300–600 K.

/pdf/thermoelectric-properties-of-a-single-graphene-sheet-and-its-3zs8l41o2p.pdf

Thermoelectric properties of a single graphene sheet and its derivatives

Density functional theory studies are reported to analyze the interaction between hydrogen sulfide (H2S) and graphene. The electron-ion interactions have been modeled using ultrasoft pseudopotentials and the exchange-correlation energies have been approximated by the method of the generalized gradient approximation in the parameterization of Perdew-Burke-Ernzerhof. Three graphene structures, one intrinsic and two with defects (vacancy and sustitution), and four H2S concentrations have been studied. The optimal geometries, binding energies, density of states (DOS) and charge density were obtained. In order to study the adsorption process three high symmetry sites were considered, namely, top, bridge, and center. The preferential adsorption structure corresponds to the center site in a physical way. The DOS of graphene-H2S systems shows a metallic behavior which coincides with the behavior of the isolated graphene. The geometrical structure of the graphene and the hydrogen sulfide remains unchanged.

/pdf/a-theoretical-analysis-of-the-role-of-defects-in-the-1ddcrp1557.pdf

J.E. Castellanos Águila

Papers

A theoretical analysis of the role of defects in the adsorption of hydrogen sulfide on graphene

Electronic band alignment at CuGaS2 chalcopyrite interfaces

Theoretical band alignment in an intermediate band chalcopyrite based material

DFT studies on the Al, B, and P doping of silicene