Metal Sulfide Catalysts Research Articles

Designing sulfide catalysts for H2S dissociation to H2 based on reaction descriptors and microkinetics

Molybdenum disulfide (MoS2) is a promising catalyst for the challenging transformation of hydrogen sulfide (H2S) into sulfur and hydrogen (H2). However, a detailed understanding of its structure-function correlation still needs to be provided. We used density functional theory calculations to extract relevant reaction indexes (binding energies and free energy barriers) over different MoS2 surfaces. We used these indexes as inspiration in developing new catalysts and a microkinetic model to compare the results, extracting insights into the reaction mechanisms and surface coverages. The turnover frequencies obtained experimentally and through microkinetic modeling are analogous, validating our approach. The findings pave the way for developing more efficient H2S decomposition catalysts and establish a descriptor-based design for other metal sulfide catalysts.

Modulating electron structure of active sites in high-entropy metal sulfide nanoparticles with greatly improved electrocatalytic performance for oxygen evolution reaction

Excellent oxygen evolution reaction (OER) electrocatalysts hold paramount significance for related clean energy conversion technologies. High-entropy materials have garnered significant interests because of their novel structures and unprecedented potentials in application. Herein, we successfully prepared a high-entropy metal sulfide catalyst, specifically (FeCoNiMnMo)Sx, through a facile method. The resulting catalyst exhibited a phase similar to CoS2 and its electrocatalytic activity was rigorously evaluated as an OER catalyst in 1 M KOH. Endowed by the synergistic effect and the modulation of electronic structures among the various metals, the (FeCoNiMnMo)Sx catalyst demonstrated exceptional water oxidation performances. Notably, it required only 290 mV of overpotential to reach 10 mA cm−2. This remarkable performance underscores the effectiveness of high-entropy sulfides as electrocatalysts. The present work supplied a new successful example for exploring the vast potential of high-entropy materials in electrocatalysis and other related fields.

Achieving Efficient Oxygen Evolution on High-Entropy Sulfide Utilizing Low Electronegativity of Al.

Efficient and stable catalysts are in high demand for accelerating the oxygen evolution reaction (OER). Herein, a high-entropy sulfide (HES) of (FeCoNiCrCuAl)S@HCS with a 3Dstructure is successfully prepared by utilizing a simple one-step solvothermal method and employed as catalyst toward OER. The lower electronegativity of Al compared to the other metal elements and its anti-corrosion character enable an outstanding OER performance of (FeCoNiCrCuAl)S@HCS with an overpotential of 253mV at 10mA cm-2 and an excellent durability after 20000 CV cycles, outperforming the commercial RuO2 and most reported metal-sulfide catalysts. Experiments coupled with theoretical calculations reveal that Al atom primarily serves as electron donor and promotes a redistribution of local electrons from Co and Cr toward adjacent Fe, Ni, and Cu sites. As a result, the Cr-Al site possesses a lowest energy barrier during the rate-determining step and works as the dominant active site for OER process. This study provides a novel insight and strategy into structural design and performance enhancement for HES materials.

Hollow-structured cobalt sulfoselenide as cathode host to enhance the kinetics and improve the energy density of lithium-sulfur batteries

Lithium-sulfur batteries are a promising next-generation battery system due to their high energy density, low cost, and environmental friendliness. However, the shuttle effect and resulting low redox kinetics are significant issues that currently hinder their development. The addition of catalysts to accelerate the redox process is a common strategy. Metal sulfide catalysts, in particular, have been widely studied due to their good affinity for sulfur and sulfides. Although metal sulfide show good adsorption performance for lithium polysulfides, their low conductivity does not significantly improve the kinetic performance of the battery. Additionally, the high molecular weight of the inactive sulfide leads to the low actual energy density of the battery. Thus, this study constructed the hollow structural cobalt sulfoselenide by replacing partial elemental sulfur in cobalt sulfide (Co3S4) with the higher metallicity element selenium (Se). This was done to increase catalytic activity and reduce the amount of inactive substances, ultimately leading to an increase in actual energy density. This strategy systematically investigated the electrical conductivity, catalytic activity, and inhibition of the shuttle effect of Co3S2Se2. It was found that cobalt sulfoselenide with a 1:1 ratio of sulfur to selenium exhibited higher catalytic activity than pure cobalt sulfide. Additionally, the hollow structure of cobalt sulfoselenide showed greater performance enhancement than bulk cobalt sulfoselenide. In the assembled lithium-sulfur battery, the initial specific capacity of 1294.7 mAh/g at 0.1C was obtained, and the capacity retention was 77.5 % after 100 cycles. On this basis, the structure–activity relationship between selenium-sulfur ratio and electrochemical properties will provide ideas for the design of microscopic cathode structures.

Engineering catalytic defects via molecular imprinting for high energy Li-S pouch cells

ABSTRACT Heterogeneous catalysis promises to accelerate sulfur-involved conversion reactions in lithium-sulfur batteries. Solid-state Li2S dissociation remains as the rate-limiting step because of the weakly matched solid-solid electrocatalysis interfaces. We propose an electrochemically molecular-imprinting strategy to have a metal sulfide (MS) catalyst with imprinted defects in positions from which the pre-implanted Li2S has been electrochemically removed. Such tailor-made defects enable the catalyst to bind exclusively to Li atoms in Li2S reactant and elongate the Li–S bond, thus decreasing the reaction energy barrier during charging. The imprinted Ni3S2 catalyst shows the best activity due to the highest defect concentration among the MS catalysts examined. The Li2S oxidation potential is substantially reduced to 2.34 V from 2.96 V for the counterpart free of imprinted vacancies, and an Ah-level pouch cell is realized with excellent cycling performance. With a lean electrolyte/sulfur ratio of 1.80 μL mgS–1, the cell achieves a benchmarkedly high energy density beyond 500 Wh kg–1.

Promoted polysulfide conversion process and improved rate performance by tin atom modified carbon in Li-S batteries

Dissolution of polysulfides limits the improvement of rate performance in Li-S batteries. Introducing catalytic agents is the key to promote polysulfide conversion process and improve rate performance of Li-S batteries. Both metallic atoms catalysts and metal sulfide catalysts can promote polysulfide conversion process. However, the comparison of catalyzing abilities between metallic atoms catalysts and metal sulfide catalysts in Li-S batteries still needs to be studied. SnS modified carbon (C/SnS) and Sn atom modified carbon (C/Sn) are obtained by controlling hydrothermal and carbonization processes in this paper. Electrochemical performance of C/SnS/S and C/Sn2S3/S composite electrodes are also studied, which are obtained by loading sulfur on C/SnS and C/Sn. Results show that C/Sn2S3/S composite electrodes possess higher rate performance (553 mAh·g−1 at 5C) than C/SnS/S composite electrodes, which is ascribe to stable catalyzing abilities of Sn atom modified carbon. Electron transportation abilities and Li-ion diffusion process are both promoted in C/Sn2S3/S composite electrodes. The comparison of catalyzing abilities between C/SnS and C/Sn composites provides reference for design and regulation of composite structures.

Novel CdLa2S4/Ni2P photocatalyst with boosting H2 evolution: Heterostructures promote photogenic carrier interface separation

Metal sulfides, often exhibited excellent photocatalytic H2 evolution ability, has attracted more and more attention, whereas their industry applications were limited due to the photocorrosion. Therefore, the inhibition of photocorrosion is the key issue to promote the industrialization of metal sulfide catalysts. In this work, CdLa2S4 /Ni2P catalysts with satisfactory H2 evolution property were designed and synthesized. Catalyst with 15 % Ni2P dosage exhibited maximum photocatalytic H2 evolution rate as 1.143 mmolh-1g−1, which was 10 times higher than that of pure CdLa2S4. Such high catalytic efficiency maintained after 5 photocatalytic cycles. According to the results of transient photocurrent and photoluminescence, the heterojunction structure formed by Ni2P and CdLa2S4 improved the separation efficiency of photogenerated electron-hole pairs, thus prompted the H2 evolution ability and the catalyst stability. Further EPR results confirmed the existence of heterojunctions in the catalyst and proposed a possible reaction mechanism. The results show that the CdLa2S4/Ni2P composite photocatalyst has good visible light response and photochemical stability, and has broad application prospects in solar driven photocatalytic decomposition of water to hydrogen production.

Eggshell membrane-derived metal sulfide catalysts for seawater splitting

A biowaste, i.e., eggshell membranes, was utilized as a versatile platform to fabricate OER electrocatalysts for seawater electrolysis.

Three-dimensional self-supporting micro-nanostructured MoS2/CoS2/CC heterojunction derived from ZIF-67 for high efficiency electrocatalytic hydrogen evolution in both acid and alkali electrolytes

In this paper, a novel three-dimensional (3D) MoS2/CoS2 micro-nano heterostructured electrocatalyst has been successfully derived from ZIF-67 on carbon cloth (CC) by a simple method of low temperature vulcanization. The metal-organic framework (MOFs) of ZIF-67 on CC was obtained at room temperature and used as both the precursor of Co and structure template to construct the 3D self-supporting spindle CoS2 nanodiscs on CC. Large amounts of 2D MoS2 nanosheets were subsequently grown on the surface of spindle-shaped CoS2 nanodiscs to form 3D self-supporting MoS2/CoS2/CC heterostructural electrocatalyst. This 3D self-supporting heterostructural electrocatalyst showed good hydrogen evolution reaction (HER) performance in both acid and alkali electrolytes. At 10 mA/cm2, the HER overpotentials of the MoS2/CoS2/CC heterostructural electrocatalyst in the alkali and acid electrolyte were 147 mV and 119 mV, and their corresponding Tafel slopes were 90.5 mV dec−1 and 111.4 mV dec−1, respectively, indicating that this MoS2/CoS2/CC heterostructural electrocatalyst had a good application prospect in the electrolysis of water to produce hydrogen. Moreover, this work provides a new idea for low-cost, scale fabrication of 3D self-supporting heterostructured transition metal sulfide catalysts.

The dual built-in electric fields across CoS/MoS2 heterojunctions for energy-saving hydrogen production coupled with sulfion degradation

Substituting the sluggish oxygen evolution reaction with the sulfur oxidation reaction can significantly reduce energy consumption and eliminate environmental pollutants during hydrogen generation. However, the progress of this technology has been hindered due to the lack of cost-effective, efficient, and durable electrocatalysts. In this study, we present the design and construction of a hierarchical metal sulfide catalyst with a gradient structure comprising nanoparticles, nanosheets, and microparticles. This was achieved through a structure-breaking sulfuration strategy, resulting in a “ball of yarn”-like core/shell CoS/MoS2 microflower with CoS/MoS2/CoS dual-heterojunctions. The difference in work functions between CoS and MoS2 induces an electron polarization effect, creating dual built-in electric fields at the hierarchical interfaces. This effectively modulates the adsorption behavior of catalytic intermediates, thereby reducing the energy barrier for catalytic reactions. The optimized catalyst exhibits outstanding electrocatalytic performance for both the hydrogen evolution reaction and the sulfur oxidation reaction. Remarkably, in the assembled electrocatalytic coupling system, it only requires a cell voltage of 0.528 V at 10 mA cm−2 and maintains long-term durability for over 168 h. This work presents new opportunities for low-cost hydrogen production and environmentally friendly sulfion recycling.

Recovery of elemental sulfur direct from nonferrous flue gas by a low-temperature Claus process with H2S as the interim reducer

Direct reduction of high concentrations of SO2 from flue gases with oxygen to produce elemental sulfur (S8) is a promising pathway, that can realize sulfur resource recycling economically and storage avoiding the expensive SO2 pre-separation procedure. However, the process is significantly restricted by the O2 oxidation in flue gas and the traditional reducing gases can hardly work efficiently because of the excessive consumption by O2. In this study, we developed a low-temperature Claus process (LTCP) to reduce SO2 to S8 in the presence of O2 (5 vol%), and the interim production of H2S was employed as the reducer carrier, which can be efficiently re-produced by the reaction of S8 with H2 or CO thereafter. Results indicated that LTCP exhibited 97.2% S8 yield with the stoichiometric ratio at 150 °C and 5 vol% of oxygen content, which were both far higher than those for H2 or CO as the reducing gases at 350 °C. Further increasing the SO2 to H2S ratios to 1:1, almost 100% of H2S can be used to selectively reduce SO2 by Claus reaction at lower temperatures, and the slip H2S can be completely suppressed. As the catalyst and the temporary storage for S8 deposit, Al2O3 shows the best performance compared with other supported metal oxide and sulfide catalysts, and the sulfur capacity even achieves 432 mg(S)/g(Cat) with only 15% breakthrough. Meanwhile, LTCP also demonstrates excellent off-line temperature-swing regeneration performance, and part of the recovered S8 can be readily used to produce H2S. These promising results can officiously resolve the intractable problem of O2 oxidation and enable sulfur recovery directly from any nonferrous smelting and other flue gases with high concentrations of SO2.

ZnS-embedded porous carbon for peroxydisulfate activation: Enhanced electron transfer for bisphenol A degradation

Transition metal sulfides have garnered increasing attention for their role in persulfate activation, a crucial process in environmental remediation. However, the function of metal sulfides without reversible valence changes, such as ZnS, remains largely unexplored in this context. Here we report ZnS-embedded porous carbon (ZnS-C), synthesized through the pyrolysis of Zn-MOF-74 and dibenzyl disulfide. ZnS-C demonstrates remarkable activity in activating peroxydisulfate (PDS) across a wide pH range, enabling the efficient mineralization removal of bisphenol A (BPA). Through electrochemical investigation and theoretical simulations of charge density distributions, we unveil that the electron transfer from BPA to PDS mediated by the ZnS-C catalyst governs the reaction. This study, both in theory and experiment, demonstrates metal sulfide as electron pump that enhances electron transfer efficiency in PDS activation. These findings redefine the role of metal sulfide catalysts, shedding new light on their potential for regulating reaction pathways in PDS activation processes.

Insights into persulfate-activated photodegradation of tinidazole and photoreduction of hexavalent chromium through β-In2S3 anchored on Ag-doped fish scale-derived HAp composite quantum dots

Herein, novel Ag/HAp/In2S3 composite quantum dots (QDs) were engineered to activate persulfate (PS) under visible light irradiation to photodegrade tinidazole (TNZ). An alkaline treatment was employed to extract hydroxyapatite (HAp) from fish scales, and a bioreduction method was used to dope HAp with Ag nanoparticles. Finally, In2S3 was grown over Ag/HAp via a facile solvothermal method. The formulated catalyst showed excellent catalytic photoactivity toward the photodegradation of TNZ and other emerging toxins with high efficiency through green and clean technology. The reaction conditions, determination of reactive species, the mechanisms, the effect of competing species, COD, and TOC removal were investigated and discussed. During 30 min of visible light irradiation, 0.24 g/L of Ag/HAp/In2S3 composite QDs degraded 96.32 ± 1.76% of 20 mg/L of TNZ at a rate constant of 0.1021 min−1 and showed a mineralization efficiency of 79.33%. The degradation intermediates were identified through HR-LCMS, and the effect of the Ag/HAp/In2S3/Vis@PS system on other pollutants and real water conditions was analyzed. Moreover, Cr(VI) photoreduction to Cr(III) was also enhanced with an efficiency of 83.63 ± 1.69% and a rate constant of 0.02648 min−1. The silver metal acted as an electron accumulator and enhanced the degradation and reduction process by increasing the electron-hole recombination time. This work elucidated the role of the metal sulfide catalyst in the activation of PS for the elimination of emerging pollutants for a cleaner environment in visible light exposure. The novel Ag/HAp/In2S3 composite QDs could prove to be a potential material for environmental remediation against various contaminants in the near future.

High Formate Selectivity and Deactivation Mechanism of CuS Nanoparticles in CO2 Electrocatalytic Reduction Reaction.

CO2 electroreduction into liquid fuels is of broad interest and benefits reducing the energy crisis and environment burdens. CuS has been reported to be a desirable candidate for CO2 electroreduction into formate; however, its formate selectivity and stability are still far from the demands of practical application. Herein, we report CuS nanoparticles exhibiting good Faradaic efficiency of formate (about 98 %) in CO2 electroreduction and its deactivation mechanism during the reaction. The deactivation of CuS was found to be associated with the reconstruction and S loss of CuS, which deteriorates the Faradaic efficiency of formate. Combined with ionic and gas analyses, the S atom in CuS was lost in the form of H2 S, SO2 , and SO4 2- , followed by the reconstruction of CuS into copper oxides. Such a catalyst reconstruction facilitates electroreductions of CO2 and H2 O, respectively, into CO and H2 , etc., resulting in the degradation of catalytical performance of CO2 electroreduction into formate. This work reveals the important role of S loss and reconstruction of metal sulfide catalysts during the electroreduction reaction, which may benefit the further development of CuS-based electro-catalyst for CO2 electroreduction.

Nanosheet-assembled transition metal sulfides nanoflowers derived from CoMo-MOF for efficient oxygen evolution reaction

Oxygen evolution reaction (OER) is a multi-electron transfer process, whose intrinsic sluggish dynamic restricts the whole process of overall water splitting (OWS). To address this issue, a porous transition metal sulfide (TMS) catalyst with rich heterojunctions was prepared by vulcanization and trace Fe doping of CoMo-based metal–organic framework (MOF). In this work, the nanoflower composed of ultrathin 2D nanosheets anchored on a nickel foam presents a layered interface that contributes to the exposure of active regions. The resulting electrode denoted as Fe@CoMo2S4/Ni3S2/NF required a low overpotential (η10 = 167 mV @ 10 mA cm−2, η50 = 260 mV @ 50 mA cm−2) in 1.0 M KOH for OER and a small cell voltage (E = 1.513 V @ 10 mA cm−2) to power OWS when coupled with commercial Pt/C. It also exhibited splendid morphological and chemical stability with virtually invariant polarization curve and flower-like appearance after 1000 CV cycles, as well as long-term durability over 100 h with a constant current density of 10 mA cm−2. This work revealed the multi-anionic regulation mechanism in the surface reconstruction of sulfide electrocatalysts, and verified that Co/Mo/Ni-based oxysulfide was the true active substance of OER, which inspired the understanding and design of multi-anionic regulated electrocatalysts.

Non-noble metal high entropy sulfides for efficient oxygen evolution reaction catalysis

Designing high activity and stable oxygen evolution reaction (OER) catalysts is essential for improving the efficiency of the water splitting reaction. The high entropy transition metal sulfide (HES) catalyst will be a promising candidate for accelerating the OER due to its high intrinsic activity and excellent stability. However, the synthesis of HES by chemical methods and the investigation of the structural evolution during the reaction remain a challenging task. In this work, a HES catalyst has been synthesized by a simple thermal injection method. All elements are uniformly distributed in HES nanoparticles, which exhibit excellent activity with an exceptionally low overpotential of 263 at current densities of 100 mA·cm−2 and a low Tafel slope of 51.5 mV·dec−1. This work demonstrates the great potential of HES catalysts as OER electrocatalysts and provides new ideas for the construction and extension of this family of compounds.

A novel sacrificial solvent method to synthesize self-supporting Co9S8/Ni3S2 heterostructure catalyst for efficient oxygen evolution reaction

Synthesizing catalysts for efficient oxygen evolution reaction (OER) with lower cost and simpler design is of significant importance to achieve sustainable hydrogen production. In this work, we propose a novel “sacrificial solvent method” for the first time. Dicobalt octacarbonyl (Co2(CO)8), dimethyl sulfoxide (DMSO), and Ni foam (NF) were used as the raw materials in the solvothermal process. DMSO played the role of both the sacrificial solvent and the sulfur source. Through the self-consumption of DMSO, we finally obtained the Co9S8/Ni3S2 heterostructure supported on the NF (Co9S8/Ni3S2@NF) in one step. The Co9S8/Ni3S2@NF catalyst exhibited excellent OER activity in alkaline environment, with an overpotential of only 264 mV at a current density of 20 mA cm−2, a low Tafel slope of 68.28 mV dec-1 and maintained its current density after 20 h of constant potential testing. This work introduces a new method for synthesizing metal sulfide catalysts using DMSO as a sacrificial solvent. It provides broader opportunities for the development of more efficient and sustainable catalysts for energy conversion and storage.

Facile Construction of Three-Dimensional Heterostructured CuCo2S4 Bifunctional Catalyst for Alkaline Water Electrolysis

Developing an efficient multi-functional electrocatalyst with high efficiency and low cost to replace noble metals is significantly crucial for the industrial water electrolysis process and for producing sustainable green hydrogen (H2) fuel. Herein, ultrathin CuCo2S4 nanosheets assembled into highly open three-dimensional (3D) nanospheres of CuCo2S4 (Cu/Co = 33:67) were prepared by a facile one-pot solvothermal approach and utilized as a bifunctional electrocatalyst for efficient overall water splitting. The as-prepared CuCo2S4 is characterized structurally and morphologically; the BET surface area of the CuCo2S4 (Cu/Co = 33:67) catalyst was found to have a larger specific surface area (21.783 m2g−1) than that of other catalysts with a Cu/Co ratio of 67:33, 50:50, and 20:80. Benefiting from a highly open structure and ultrathin nanosheets with excellent exposure to catalytically active sites, CuCo2S4 (Cu/Co = 33:67) is identified as an efficient catalyst for the proton reduction and oxygen evolution reactions in 1 M KOH with an overpotential of 182 and 274 mV at 10 mA cm−2, respectively. As expected, a low cell voltage of 1.68 V delivers a current density of 10 mA cm−2. Stability and durability are also greatly enhanced under harsh alkaline conditions. Therefore, this work provides a simple strategy for the rational design of spinel-based transition metal sulfide catalysts for electrocatalysis.

Coral-shaped Mn-CuS with hierarchical pores and crystalline defects for high-efficiency H2O2 production via electrocatalytic two-electron reduction

We report the development of non-noble transition metal sulfide catalysts Mn-CuS-x for high-efficiency and selective H2O2 production. In this study, we synthesized Mn-CuS-x with coral-shaped hierarchical porous structure through one-pot hydrothermal reaction. The Mn-CuS-x possesses large specific surface area with plenty of crystalline defects via heteroatom doping of Mn. The Mn-CuS-x kinetically favored 2e− pathway over 4e− pathway, resulting in high selectivity (>92%) to H2O2 production and high H2O2 concentration (∼24.5 mM at 0.6 V vs. RHE) within 3 h for the optimized Mn-CuS-2 catalysts (synthesized with a molar ratio of 1:3:8 (MnCl2·4 H2O: CuCl2·2 H2O: C2H5NS)). The Mn-CuS-2 showed excellent stability, indicating that the Mn-CuS electrocatalysts can simultaneously achieve both high stability and enhanced H2O2 production. Our first-principles calculations further confirmed that the heteroatom Mn doping to CuS thermodynamically makes the 2e–-ORR pathway more favorable. This study provides a green, low-cost, and efficient route to produce H2O2, which is very promising for generating chemicals and liquid fuels.

The Application of Transition Metal Sulfide Nanomaterials and Their Composite Nanomaterials in the Electrocatalytic Reduction of CO2: A Review

Electrocatalysis has become an important topic in various areas of research, including chemical catalysis, environmental research, and chemical engineering. There have been a multitude of different catalysts used in the electrocatalytic reduction of CO2, which include large classes of materials such as transition metal oxide nanoparticles (TMO), transition metal nanoparticles (TMNp), carbon-based nanomaterials, and transition metal sulfides (TMS), as well as porphyrins and phthalocyanine molecules. This review is focused on the CO2 reduction reaction (CO2RR) and the main products produced using TMS nanomaterials. The main reaction products of the CO2RR include carbon monoxide (CO), formate/formic acid (HCOO−/HCOOH), methanol (CH3OH), ethanol (CH3CH2OH), methane (CH4), and ethene (C2H4). The products of the CO2RR have been linked to the type of transition metal–sulfide catalyst used in the reaction. The TMS has been shown to control the intermediate products and thus the reaction pathway. Both experimental and computational methods have been utilized to determine the CO2 binding and chemically reduced intermediates, which drive the reaction pathways for the CO2RR and are discussed in this review.