An advanced FeCoNi nitro-sulfide hierarchical structure from deep eutectic solvents for enhanced oxygen evolution reaction

Ionic Liquid/Deep Eutectic Solvent-Mediated Calcining Synthesis of Cobalt-Based Electrocatalysts for Water Splitting

The recent advancements of ionic liquids (ILs) and deep eutectic solvents (DESs) in the synthesis of cobalt-based catalysts for water splitting is reviewed. ILs and DESs possess unique physical and chemical properties, serving as solvents, templates, and reagents. Combined with calcination techniques, their advantages can be fully leveraged, enhancing the stability and activity of resulted catalysts. In these solvents, not only are they suitable for simple one-step calcination, but also applicable to more complex multi-step calcination, suitable for more complex reaction conditions. The designability of ILs and DESs allows them to participate in the reaction as reactants, providing metal and heteroatoms, simplifying the preparation system of cobalt phosphide, sulfide, and nitride. This work offers insights into design principles for electrocatalysts and practical guidance for the development of efficient and high-performance materials for hydrogen production and energy storage systems.

Utilization of Cobalt and its Oxide/Hydroxide Mediated by Ionic Liquids/Deep Eutectic Solvents as Catalysts in Water Splitting

With the ever-growing global demand for sustainable energy solutions, hydrogen has garnered significant attention as a clean, efficient, and renewable energy source. In the field of hydrogen production, catalyst research stands out as one of the foremost areas of focus. In recent years, the preparation of electrocatalysts using ionic liquids (ILs) and deep eutectic solvents (DESs) has attracted widespread attention. ILs and DESs possess unique physicochemical properties and are recognized as green media as well as functional materials. Cobalt-based catalysts have proven to be efficient electrocatalysts for water splitting. Incorporating ILs or DESs into the preparation of cobalt-based catalysts offers a remarkable advantage by allowing precise control over their structural design and composition. This control directly influences the adsorption properties of the catalyst's surface and the stability of reaction intermediates, thereby enabling enhanced control over reaction pathways and product selectivity. Consequently, the catalytic activity and stability of cobalt-based catalysts can be effectively improved. In the process of preparing cobalt-based catalysts, ILs and DESs can serve as solvents and templates. Owing to the good solubility of ILs and DESs, they can efficiently dissolve raw materials and provide a special nucleation and growth environment, obtaining catalysts with novel-structures. The main focus of this review is to provide a detailed introduction to metal cobalt and its oxide/hydroxide derivatives in the field of water splitting, with a particular emphasis on the research progress achieved through the utilization of IL and DES. The aim is to assist readers in designing and synthesizing novel and high-performance electrochemical catalysts.

Deep Eutectic Solvent-Mediated Electrocatalysts for Water Splitting

As green, safe, and cheap solvents, deep eutectic solvents (DESs) provide tremendous opportunities to open up attractive perspectives for electrocatalysis. In this review, the achievement of DESs in the preparation of catalysts for electrolytic water splitting is described in detail according to their roles combined with our own work. DESs are generally employed as green media, templates, and electrolytes. A large number of hydrogen bonds in DESs result in supramolecular structures which have the ability to shape the morphologies of nanomaterials and then tune their performance. DESs can also serve as reactive reagents of metal electrocatalysts through directly participating in synthesis. Compared with conventional heteroatom sources, they have the advantages of high safety and designability. The "all-in-one" transformation strategy is expected to realize 100% atomic transformation of reactants. The aim of this review is to offer readers a deeper understanding on preparing DES-mediated electrocatalysts with higher performance for water splitting.

Ionic Liquid/Deep Eutectic Solvent-Mediated Ni-Based Catalysts and Their Application in Water Splitting Electrocatalysis

Nickel-based electrocatalysts have been widely used to catalyze electrocatalytic water splitting. In order to obtain high-performance nickel-based electrocatalysts, using ionic liquids and deep eutectic solvents mediated their preparation has received increasing attention. Firstly, ionic liquids and deep eutectic solvents can act as media and templates for the preparation of Ni-based nanomaterials with novel structures and excellent catalytic activity. Secondly, ionic liquids and deep eutectic solvents can be employed as reactants to participate the synthesis of catalysts. Their participation not only increase the catalytic performance, but also simplify the reaction system, improve reproducibility, reduce emissions, and achieve atomic economy. On the basis of the work of our group, this review gives a detailed description of the impressive progress made concerning ionic liquids and deep eutectic solvents in the preparation of nickel-based electrocatalysts according to their roles. We also point out the challenges and opportunities in the field.

Photoelectrochemical oxygen evolution with interdigitated array electrodes: the example of TiO2

The catalytic reactions of photoelectrochemical water splitting attracts tremendous attention as a promising strategy for clean energy production. And the research on reaction mechanism is particularly important in design and developing new catalysts. In this work, the special electrochemical tool of interdigitated array (IDA) electrodes was utilized in investigating the photoelectrochemical oxygen evolution reaction process and detecting the reaction productin situwith the generation-collection mode. TiO₂was taken as a model catalyst and was decorated onto the IDA generator electrode through an electrophoresis method, so that the photoelectrochemical water splitting can take place on the IDA generator and the reaction product can be detected directly with the IDA collector in real time. It is found that TiO₂can be successfully decorated onto the surface of IDA electrode with the expected photoelectrochemical activity, and the generation-collection mode reveals and distinguishes the production of O₂from the overall photoelectrochemical current on TiO₂generator. The mass transfer process of O₂from the TiO₂generator to the collector could be observed as well. Large overall current at high potential range indicates the possible increasing production of the byproducts or nonfaradaic current.

Microwave-Assisted Solution Synthesis of Metastable Intergrowth of AgInS2 Polymorphs

The intergrowth of stable and metastable AgInS2 polymorphs was synthesized using a microwave-assisted synthesis. The samples were synthesized in water and in a deep eutectic solvent (DES) consisting of choline chloride and thiourea. An increase in the metal precursor concentration improved the crystallinity of the synthesized samples and affected the particle size. AgInS2 cannot be synthesized from crystalline binary Ag2S or In2S3 via this route. The solution synthesis reported here results in the intergrowth of the thermodynamically stable polymorph (space group I4¯2d, chalcopyrite structure) and the high-temperature polymorph (space group Pna21, wurtzite-like structure) that is metastable at room temperature. A scanning transmission microscopy (STEM) study revealed the intergrowth of tetragonal and orthorhombic polymorphs in a single particle and unambiguously established that the long-thought hexagonal wurtzite polymorph has pseudo-hexagonal symmetry and is best described with the orthorhombic unit cell. The solution-synthesized AgInS2 polymorphs intergrowth has slightly lower bandgap values in the range of 1.73 eV–1.91 eV compared to the previously reported values for tetragonal I4¯2d (1.86 eV) and orthorhombic Pna21 (1.98 eV) polymorphs.

Ionic Liquids and Deep Eutectics as a Transformative Platform for the Synthesis of Nanomaterials

Ionic liquids (ILs) are becoming a revolutionary synthesis medium for inorganic nanomaterials, permitting more efficient, safer and environmentally benign preparation of high quality products. A smart combination of ILs and...

2D amorphous bi-metallic NiFe nitrides for a high-efficiency oxygen evolution reaction

Two-dimensional bi-metallic NiFe nitrides (2D NiFe-N) are successfully synthesized in the designed ternary deep eutectic solvents under the guidance of DFT calculations. Taking advantage of the unique properties of large-size, ultrathin amorphous 2D structure and modulable electronic structure, the NiFe_0.05-N exhibits extraordinary OER performance with relatively low overpotential of 238 mV at 10 mA cm^-2 and durable stability.

Time-dependent air quality and pollutant concentration in the Jingjinji region: future gas capture by green solvents

Time-dependent air quality, pollutant concentration, major pollutants and pollution level in Jingjinji (around Beijing) from 2016 to 2020 are analyzed.

Recent progress with electrocatalysts for urea electrolysis in alkaline media for energy-saving hydrogen production

Urea electrolysis is a promising energy-saving avenue for hydrogen production owing to the low cell voltage, wastewater remediation and abundant electrocatalysts.

NiFe LDH/CuO nanosheet: a sheet-on-sheet strategy to boost the active site density towards oxygen evolution reaction

The amount of active sites of a catalyst is of great importance to enhance the oxygen evolution reaction (OER) activity. Here, the sheet-on-sheet strategy is proposed to effectively increase the density of active sites of NiFe layered double hydroxide (NiFe LDH) catalyst in terms of structural engineering. As a non-precious electrocatalyst for the OER, NiFe LDH is grown directly on CuO nanosheets. As a result, the received NiFe LDH/CuO nanosheet catalyst with sheet-on-sheet structure shows an ultralow overpotential of 270 mV at 20 mA cm⁻², much lower than that of RuO₂ as a benchmark. The CuO nanosheets, as substrate, play the vital role in downsizing the NiFe LDH, leading to the raised active site density.

The amount of active sites of a catalyst is of great importance to enhance the oxygen evolution reaction (OER) activity.