Simple Sulfurization Research Articles

Preparation of Titanium Dioxide (TiO<sub>2</sub>) from Waste of Polymetallic Ore Processing <i>via</i> Sulfurization Treatment

Various experimental conditions were applied to extract titanium oxide from the waste of polymetallic ore. X-ray diffraction (XRD) analysis confirms that the waste of polymetallic ore contains including various minerals such as almandine (Fe,Mg,Ca)3Al2Si3O12, brownmillerite (FeAlO3(CaO)2), quartz (SiO2), magnetite (Fe3O4). Using H2SO4 acid with a concentration of 93% in the S/L mass ratio of 1:1.5 at 140 °C is suggested as an optimum reaction condition. Its hydrolysis subsequently leads to the formation of the titanyl sulfate (TiOSO4), and relatively pure titanium oxide is obtained through precipitation and calcination at 600 °C. The observed band gap value of 3.2 eV for the obtained TiO2 corresponds to the typical band gap value of anatase-type TiO2. We calculated the crystallite size of extracted anatase-type titanium oxide according to the Debye-Scherrer equation it was determined to be 96.35 nm. Fully reflecting X-ray fluorescence (XRF) determined that the purity of extracted TiO2 is 93.18%. This report presents a newly developed process that enables the production of relatively high-purity TiO2 (93.18%) from the waste of polymetallic ore (TiO2 5.39%) by a simple sulfurization process.

A preliminary investigation into the potential of Ge-enhanced Cu2SnS3 (CTS) thin-film applications for water-splitting photoelectrodes

This study explores the potential of Ge-enhanced Cu2SnS3 (CTS) thin-films as photoelectrode materials for water splitting grown through a simple sulfurization process. The addition of Ge to CTS enabled tuning the bandgap and improved the photocurrent density. Films sulfurized at 520 °C exhibit enhanced grain size and reduced grain boundaries, which contribute to increased carrier transport efficiency. By optimizing Ge content and sulfurization conditions, the Cu2(Sn1−x ,Ge x )S3 films demonstrate promising capabilities for efficient green hydrogen production. This work lays the groundwork for developing advanced photoelectrodes and highlights the need for further refinement to maximize performance for practical applications.

Heteroatom Sulfur-Modified ZIF-8 Derived Zn, N Co-Doped Carbon Nanocages as Highly Efficient ORR Catalysts for Zn-Air Batteries

Carbon-based electrocatalysts derived from zeolitic imidazolate framework-8 (ZIF-8) have garnered significant attention, owing to their structural advantages, high surface area, and tunable active sites. Herein, we report the synthesis of heteroatom sulfur (S) modified ZIF-8 derived carbon nanocages (ZnS@N/S-C) for oxygen electrocatalysis through self-assembly and two-step pyrolysis. The resultant ZnS@N/S-C exhibits catalytic activity towards oxygen reduction reaction (ORR) with high half-wave potential (0.86 V) and stability (91.4%), separately, which is comparable to or superior to Pt/C. Furthermore, the application of ZnS@N/S-C as a cathode for Zn-air batteries (ZABs) demonstrates performance metrics such as an open-circuit voltage of 1.407 V, a power density of 114.4 mW cm−2, and a specific capacity of 764.6 mAh gZn −1, etc surpassing Pt/C. The performance of ZnS@N/S-C can be attributed to the fact that the introduction of S significantly increases the specific surface area, pore volume, and defect extent of the catalyst, while optimizing the electronic structure and generating ZnS active nanocrystals. This work employs a simple sulfurization strategy to enhance the ORR activity of ZIF-8-derived Zn-based catalysts with fully filled 3d orbitals, providing guidance for the development of such materials.

Flower-like iron sulfide/cobaltous sulfide heterostructure as advanced electrocatalyst for oxygen evolution reaction

Developing efficient non-noble metal catalysts is crucial for promoting the electrochemical production of oxygen from water. In this work, a flower-like FeS/Co3S4 heterostructure composite on carbon cloth can be fabricated with a simple sulfurization method. As-prepared FeS/Co3S4 composite shows excellent oxygen evolution reaction (OER) performance with a low overpotential of 252 mV at 10 mA cm−2 and a small Tafel slope of 58 mV dec−1, better than the FeS and Co3S4 electrodes. In addition, the FeS/Co3S4 composite displays outstanding structural stability with any decay over long-time testing. The improved OER catalytic performance of FeS/Co3S4 composite is ascribed to the increased specific surface area and formation of FeS/Co3S4 heterojunction. Besides, theoretical calculation results also show that the FeS/Co3S4 heterojunction possesses a stronger adsorption ability to ∗OH, which is more favorable to the OER than the single FeS and Co3S4 counterpart. Our work has paved a new way of exploring high-efficient catalysts for OER.

Self-Powered UV Photodetectors Based on Heterojunctions Composed of ZnO Nanorods Coated with Thin Films of ZnS and CuI

A simple, inexpensive solution process is used to deposit γ-CuI thin films, and many aspects of the films, such as morphology, crystalline phase, and its optical and electrical properties on annealing are studied. All of the grown films exhibited p-type conductivity and an average transmittance of 70 to 80% in the visible region. The film annealed at 200 °C is observed to be relatively smooth with root-mean-square roughness of 13.25 nm. CuI films annealed at 200 °C displayed a hole mobility of 0.53 cm2/Vs and a hole concentration of 8.36 × 1018 cm–3. Additionally, the potential of γ-CuI as a p-type material for photodetection is explored by fabricating transparent hybrid ultraviolet (UV) photodetectors based on p-CuI/n-ZnO nanorods and p-CuI/n-ZnS/ZnO nanostructures. The high-resolution transmission electron microscopy (HRTEM) image showed that the ZnO nanorods grew as a single crystal along the [001] direction and smaller CuI attached on their surface. A simple sulfurization procedure has created a poly-nanocrystalline ZnS shell layer over the ZnO nanorods. Crucial photodetector parameters such as responsivity, external quantum efficiency, and detectivity are analyzed with different illumination intensities and incident wavelengths. Under self-powered conditions, upon illumination with 372 nm and intensity of 0.25 mW/cm2, the p-CuI/n-ZnO nanorod showed significant responsivity of 25.11 mA/W and detectivity of 4.59 × 1013 Jones. Insertion of the ZnS layer between the ZnO and CuI has enhanced these parameters to 43.85 mA/W and 3.84 × 1014 Jones, respectively. This research underlines the potential of p-type CuI as a transparent, high-performance optoelectronic material.

Construction of hierarchical ZnS/MoS2 bimetallic sulfides heterostructures for high – performance sodium ion batteries

The rational design and construction of bimetallic hierarchical nanostructures are effective strategies for the development of conversion alloying reaction anode for sodium ion batteries (SIBs). Herein, novel hierarchical ZnS/MoS2 bimetallic sulfides are designed and fabricated via a simple sulfuration process, in which ZnS/MoS2 nanoparticles are encapsulated in Zn/Mo bimetallic imidazolate framework (Zn/Mo BIFs) derived nitrogen doped carbon frameworks with covering reduced graphene oxide (ZnS@MoS2/NC@rGO). The derived nitrogen doped carbon and graphene nanosheets can enhance electrical conductivity, and accommodate volume changes of ZnS/MoS2 on the cycling. Meanwhile, the ZnS-MoS2 heterostructure accelerates diffusion dynamics in the interface, and promotes the charge transfer rate. Due to the compositional and structural features, the obtained ZnS@MoS2/NC@rGO sample delivers superior sodium storage performance, which achieves a specific capacity of 480 mAh/g at 0.2 A/g over 100 cycles, and good rate capability of 308 mAh/g at 4 A/g. The full SIBs are fabricated by ZnS@MoS2/NC@rGO anode with homemade Na3V2(PO4)3/C cathode which exhibit the high energy density of 127.8 Wh kg−1 at the power density of 105.9 W kg−1. The preparation strategy manifests an effective and simple method to in situ fabricate hierarchical hetero-interfaces bimetallic sulfides/carbon anode materials for SIBs.

High-performance lithium-ion capacitor based on N, S co-doped porous foam carbon derived from bamboo

Based on long cyclic life and high power/energy density, the lithium-ion capacitor (LIC) has a growing trend towards applications on the energy reserve side. Nevertheless, the imbalance of storage capacity and reaction kinetic between cathode and anode is a major obstacle to achieving high-performance LIC. Herein, N, S co-doped porous foam carbon derived from bamboo (BLZSC) is prepared via a template method coupled with chemical activation. BLZSC as the cathode presents a high-specific surface area (SSA) of 2288.03 m2 g−1 and a superior capacitive capability. Furthermore, nano-ZnS/porous carbon derived from bamboo (CZS) is prepared via a simple sulfuration method, which is made up of nano-ZnS uniformly distributed on a carbon framework. CZS as the anode shows a fine rate performance, and the capacitive-dominated mechanism in the electrochemical reaction contributes to achieving the behavior of fast charge-discharge. The CZS anode and BLZSC cathode are employed to assemble the LIC. What's more, the CZS//BLZSC LIC can achieve a high energy density of 158 Wh kg−1 with a power density of 10,005 W kg−1 and prolonged cyclic life (capacitance retention of 79.19% after 8000 cycles). This study suggests N, S co-doping can further enhance the electrochemical performance based on high-SSA, which has a fine using prospect in the energy reserve side.

Sintered Ni metal as a matrix of robust self-supporting electrode for ultra-stable hydrogen evolution

For the self-supporting catalysts of Hydrogen evolution reaction (HER), the rational design and fabrication of substrate with porous structure and sufficient mechanical strength are critical to promoting the industrial HER application. In this work, a novel porous sintered Ni metal as the matrix for supporting catalysts was successfully prepared by powder metallurgy, and a self-supporting electrode for HER was fabricated via a simple sulfurization process on this sintered Ni metal matrix. For instance, MoS2/Ni3S2 nanorods (NRs) were vertically grown on the as-sintered porous Ni matrix, and the morphology of the sintered Ni matrix significantly affected the growth of MoS2/Ni3S2 NRs. The [email protected] Ni electrode shows a low overpotential of η10 = 56 mV and Tafel slope of 82 mV dec−1. Compared with [email protected] foam, the [email protected] Ni exhibits superior stability, where no exfoliation and cracks are observed on the surface of the electrode after 5000 CV cycles. Ultra-high stability and long-term durability are obtained over 100 h even at high potentials of 200 and 300 mV. Moreover, the tensile strength of the as-obtained electrode based on the sintered Ni manifests nearly 260 times higher than that of [email protected] foam, evidencing an excellent mechanical property. This work provides an idea for the preparation of self-supporting metal-based catalytic electrodes in large-scale hydrogen production.

Cobalt sulfide nanosheets derived from sulfurization of Prussian blue analogue as an enhanced catalyst for activating monopersulfate to degrade caffeine

As caffeine (CAF) is extensively consumed as food additives and medication, CAF has been continuously released into aquatic environment, causing threats to ecology because of its high solubility and persistency. While cobalt sulfides have received increasing attention for activating monopersulfate (MPS), almost no studies have been conducted to investigate cobalt sulfides to degrade CAF. Thus, the aim of this study is to investigate cobalt sulfide for activating MPS to degrade CAF. Specifically, a unique cubic cluster of cobalt sulfide nanosheets (CoSNS) is developed through a simple sulfurization of cobaltic Prussian Blue Analogue (Co-PBA) (Co3[Co(CN)6]2) under very mild condition (25 °C) to convert Co-PBA to CoSNS. CoSNS could exhibit much higher catalytic activities than its precursor Co-PBA, and the benchmark catalyst of MPS activation, Co3O4, for activating MPS to degrade CAF in 45 min. Ea of CAF degradation (24.3 kJ/mol) by CoSNS+MPS is also significantly lower than many reported Ea values, validating that CoSNS is an advantageous and highly-efficient catalyst for MPS activation to degrade CAF. The activation mechanism of CoSNS towards MPS activation is also realized using electron spin resonance. Degradation pathway of CAF degradation by CoSNS+MPS is also investigated by mass spectrometry to provide insights into degradation behaviors.

Cobalt sulfide nanofilm-assembled cube as an efficient catalyst for activating monopersulfate to degrade UV filter, 4,4′-dihydroxybenzophenone, in water

As hydroxylated benzophenones (HBPs) represent most typical UV filters and UV stabilizers, increasing release of HBPs into the aquatic environment has caused serious threats to the aquatic ecology. Among various HBPs, 4,4′-Dihydroxybenzophenone (4HBP) receives growing attentions as an emerging contaminant due to its potential toxicity of endocrine disrupting effect. For establishing useful techniques to remove 4HBP from water, this study, as the first study, aims to develop cobalt sulfide as a heterogeneous catalyst to activate monopersulfate (MPS) for generating sulfate radical (SO 4 •− ) to degrade 4HBP. Especially, a unique cubic assembly of cobalt sulfide nanofilms (CSNF) is developed through a simple sulfurization of Prussian Blue (PB) in the form of Co 3 [Co(CN) 6 ] 2 to transform this PB to CSNF. Such a resulting CSNF exhibits much higher catalytic activities than the pristine PB, and the reference catalyst, Co 3 O 4 , for activating MPS to degrade 4HBP in terms of degradation extents and kinetics. With very low dosages of CSNF = 50 mg/L and MPS = 100 mg/L, 5 mg/L of 4HBP could be fully eliminated in 15 min, validating that CSNF is a promising catalyst for activating MPS to 4HBP. E a of 4HBP degradation by CSNF-activated MPS is also determined as 68 kJ/mol. The activation mechanism and degradation pathway of 4HBP degradation by CSNF-activated MPS is investigated using electro paramagnetic resonance and mass spectrometer, respectively, to further to provide insights into degradation behaviors for developing optimal sulfate-radical-based advanced oxidation processes of 4HBP degradation.

Construction of a TiO2 heterostructure nanowire with a sulfurized shell via a simple sulfurization process for enhanced photoelectrochemical water oxidation

Promoted charge transport and separation as well as excellent light harvesting ability play a key role in enhancing photoelectrochemical (PEC) performance. Herein, a simple sulfurization approach was developed for forming polycrystalline S-doped TiO2 shell on the single crystalline TiO2 nanowire surface to form the TiO2/S-doped TiO2 core-shell homostructure. With the sulfurization time, the light harvesting ability, separation efficiency and carrier density increased for such homostructures. As a result, the highest photocurrent densities of 1.24 mA/cm2 at 1.23 V versus RHE was achieved over the TiO2/S-doped TiO2 core-shell homostructure sulfurized for 15 h, corresponding to 67.6% improvement in photocurrent density compared with the pristine TiO2. This work reveals a relatively simple strategy to simultaneously enhance light absorption and electron-hole pair separation.

Sb2S3/TiO2 Heterojunction Photocathodes: Band Alignment and Water Splitting Properties

Antimony sulfide (Sb2S3) is a promising light-absorbing semiconductor for photovoltaic applications, though it remains vastly unexplored for photoelectrochemical water splitting. Sb2S3 was synthesized by a simple sulfurization of electrodeposited antimony metal at relatively low temperatures (240–300 °C) with elemental sulfur. Using a TiO2 buffer layer and a platinum co-catalyst, photocurrent densities up to ∼9 mA cm–2 were achieved at −0.4 V vs RHE in 1 M H2SO4 under one sun illumination. Using X-ray photoelectron spectroscopy band alignment studies and potential-dependent incident photon-to-current efficiency measurements, a conduction band offset of 0.7 eV was obtained for the Sb2S3/TiO2 junction as well as an unfavorable band bending at the heterointerface, which explains the low photovoltage that was observed (∼0.1 V). Upon inserting an In2S3 buffer layer, which offers a better band alignment, a 0.15 V increase in photovoltage was obtained. The excellent photoelectrochemical water splitting performance and the identification of the origin of the low photovoltage of the Sb2S3 photocathodes in this work pave the way for the further development of this promising earth-abundant light-absorbing semiconductor for solar fuel generation.

Visible range photoresponse of vertically oriented on-chip MoS2 and WS2 thin films

The excellent electrical properties of transition metal dichalcogenide (TMD) 2D materials promise a competitive alternative to traditional semiconductor materials for applications in optoelectronics, chemical sensing, as well as in energy harvesting and conversion. As the typical synthesis methods of TMDs produce nanoparticles, such as single or multi-layered nanoflakes, subsequent strenuous integration steps are necessary to obtain devices. Direct synthesis of the material on substrates would simplify the process and provide the means for large-scale integration and production of practical devices. In our approach, we synthesize MoS2 and WS2 thin films with a simple sulfurization of the respective metal films deposited by sputtering on Si/SiO2 chips, and study their optoelectrical properties at wavelengths of 661 nm, 552 nm, and 401 nm using pulsed lasers. Both TMD thin films are found to show photoresponsivities of up to ∼5 × 10−6 A W−1 with corresponding quantum efficiencies of ∼10−5, which are unexpectedly moderate, and can be attributed to their columnar microstructure, in which the basal planes of the hexagonal lattices are perpendicular to the substrate, thus, limiting the electron transport in the films parallel to the plane of the substrate.

Metal–Organic Framework-Derived Cu-Doped Co9S8 Nanorod Array with Less Low-Valence Co Sites as Highly Efficient Bifunctional Electrodes for Overall Water Splitting

One of the main goals of current renewable energy research is continuously developing low-cost, robust, and environmentally friendly electrocatalysts to replace scarce and unstable precious metal catalysts. Hence, a novel high-performance electrocatalytic water-splitting material based on a metal–organic framework (MOF)-derived Cu-doped Co9S8 nanorod array was successfully prepared. Using 1,3,5-benzenetricarboxylic acid (H3BTC) as a ligand, a CuCo MOF (CuCo-MOF) nanobelt array precursor was prepared and then transformed into a Cu-Co9S8 nanorod by a simple sulfurization process using thioacetamide as a sulfur source. It is worth noting that the intermediate CuCo-MOF nanobelts play a key role in the generation of nanostructures of the Cu-doped Co9S8 nanorod array. As one of the most promising bifunctional electrocatalysts reported, the Cu-doped Co9S8-6h only needs 260 mV to drive 50 mA cm–2 for oxygen evolution reaction and 62 mV to drive 10 mA cm–2 for hydrogen evolution reaction. When the Cu-doped Co9S8-6h was used as an electrode in a self-made two-electrode system, it requires only 1.49 V of cell voltage to drive 10 mA cm–2, which is one of the smallest open-circuit voltages reported. Density functional theory results show that the superior performance of the Cu-doped Co9S8-6h is attributed to increased conductivity and increased water adsorption energy because of Cu doping. By comparing the water adsorption energy of Co2+, Cu2+, and Co3+, it is proved that the active Cu2+ replaces the inert Co2+, and less low-valence Co2+ sites make the Cu-doped Co9S8-6h show superior catalytic activity. These results demonstrate that the Cu-doped Co9S8-6h nanorod array can be used as an excellent bifunctional electrocatalyst for overall water splitting, and this work will provide an excellent synergistic strategy to energy storage and conversion.

Advanced battery-supercapacitor hybrid device based on Co/Ni-ZIFs-derived NiCo2S4 ultrathin nanosheets electrode with high performance

Battery-supercapacitor hybrid device (BSH) consisted of a battery-type electrode and a capacitor-type electrode is a promising candidate for both high energy and power density energy storage systems. In an effort to design a high-performance battery-type electrode of BSH, we propose a facile and artful two-step strategy to obtain NiCo2S4 ultrathin nanosheets by utilizing bimetallic Co/Ni-ZIFs as a precursor. NiCo2S4 nanosheets are directly grown on nickel foam via this method, which involves the growth of Co/Ni-ZIFs and the morphology of Co-Ni-S/NF transforms into ultrathin nanosheets through a simple sulfuration procedure. The as-prepared Co1Ni1-S/NF electrode achieves a high specific capacity of 301.1 mAh g−1 at 2 A g−1, which benefits from the synergistic interplay between Co and Ni ions and the unique 3D nanoarchitectures constructed by 2D ultrathin nanosheets. Moreover, Co1Ni1-S/NF and activated carbon/NF are chosen for fabricating a battery-supercapacitor hybrid device. The assembled Co1Ni1-S/NF//AC/NF BSH exhibits a large energy density of 48.65 W h kg−1 at a power density of 8.51 kW kg−1, a specific capacity of 80.56 mAh g−1 at 1 A g−1 and a remarkable stability over 5000 cycles at 5 A g−1. The encouraging results could provide new insights for energy storage systems.

Preparation of Fe promoted MoS2 catalysts for the hydrodeoxygenation of p-cresol as a model compound of lignin-derived bio-oil

Fe promoted MoS2 catalysts were prepared by one-step hydrothermal method and then applied into the hydrodeoxygenation (HDO) of p-cresol as a model compound of lignin-derived bio-oil. The as-prepared samples had FeS2 and MoS2 phases with low crystallinity. After further hydrogen-treatment at 250 °C in dodecane, some peaks to FeS phase were observed. The surface area of Fe promoted MoS2 catalyst decreased firstly and then increased with Fe content in the catalysts increasing. In the HDO of p-cresol, the addition of Fe sulfides into MoS2 enhanced conversion and toluene selectivity. When the Fe/Mo molar ratio is 0.7:1, the conversion and deoxygenation degree reached up to 96.3% and 95.7% after reaction at 250 °C for 3 h, respectively. The high HDO activity was attributed to the synergistic effect and contact surface area between Fe sulfides and MoS2. During the HDO recycling reaction, the deactivation was observed, which resulted from the sulfur loss and the formation of Fe oxides, but its activity could be regenerated after a simple sulfuration procedure.

Efficient and durable electrochemical hydrogen evolution using cocoon-like MoS2 with preferentially exposed edges

High-density cocoon-like molybdenum sulfide (MoS2) nanostructures have been fabricated by thermal oxidation of a metallic Mo foil, followed by a simple sulfurization process under hydrothermal conditions. The MoS2 layer thickness is determined by that of the pre-formed oxide layer on Mo foils which can be readily tuned by thermal oxidation duration. The morphology and microstructure of the as-fabricated MoS2 nano-cocoons are investigated in detail by SEM, XRD, Raman spectroscopy, and TEM. The results show that the cocoons consist of many vertically aligned ultrathin MoS2 nanosheets with preferentially exposed edges, and that the MoS2 layer is intimately bonded to the underneath Mo substrate for samples having a small layer thickness. Electrochemical tests demonstrate that all MoS2-Mo cathodes exhibit high electrocatalytic activities, small Tafel slopes and good long-term stability for the hydrogen evolution reaction (HER). The outstanding HER performance can be attributed to the existence of abundant electrocatalytically active edge sites and structural defects, and to the intimate electrical contact between MoS2 and metallic Mo and the bind-free nature of the electrode, which facilitate electron transfer. Given the high electrocatalytic performance and the easy fabrication procedure, Mo supported cocoon-like MoS2 holds substantial promise to substitute platinum for use to catalyze HER in water electrolyzers.

Improved photovoltaic and grain boundary characteristics of single elementary target-sputtered Cu2ZnSnSe4 thin films by post sulfurization/selenization process

A potential way to improve the quality of Cu2ZnSnSe4 absorber thin film by a one step process of sputtering using a single elementary target is proposed for thin film solar cells. As critical parameters, different S/Se ratios and grain boundary characteristics are achieved by adjusting sequential sulfurization and selenization post-treatment. The simple sulfurization of as-deposited film at 530 °C in H2S is not effective in raising the performance but the additional Se annealing at a shorter duration of 5 min improves conversion efficiency from 0.12 to 3.21% with a drastic increase of the open circuit voltage. Positively-charged grain boundaries with narrow potential peaks seem to play a critical role for effective exciton separation and higher efficiency. The improvement is also understood as related to well-defined microstructures and the variable optical band gap.

Studies on bull spermatozoal isoantigens

Promoted charge transport and separation as well as excellent light harvesting ability play a key role in enhancing photoelectrochemical (PEC) performance. Herein, a simple sulfurization approach was developed for forming polycrystalline S-doped TiO2 shell on the single crystalline TiO2 nanowire surface to form the TiO2/S-doped TiO2 core-shell homostructure. With the sulfurization time, the light harvesting ability, separation efficiency and carrier density increased for such homostructures. As a result, the highest photocurrent densities of 1.24 mA/cm2 at 1.23 V versus RHE was achieved over the TiO2/S-doped TiO2 core-shell homostructure sulfurized for 15 h, corresponding to 67.6% improvement in photocurrent density compared with the pristine TiO2. This work reveals a relatively simple strategy to simultaneously enhance light absorption and electron-hole pair separation.