Faradic Efficiency Research Articles

Prussian blue analogues-Derived Iron-Cobalt carbon fiber Binder-Free electrodes for electrocatalytic nitrate reduction

Developing a highly selective and efficient electrocatalytic system for nitrate reduction reaction (NO3RR) is of great significance but still remains challenging for environmental remediation and energy utilization. Herein, we constructed a binder-free cathode consisted of iron-cobalt Prussian blue analogues-based bimetal derived carbon fiber (FC-PBAFC) to enhance NO3RR performances. Significantly, high NO3−-N removal capacity of 169.1 mgN h−1 gcat-1, excellent ammonia Faradic efficiency (FE) of 83.2 ± 0.7 % and high ammonia selectivity of 99.3 ± 0.6 % were achieved by FC-PBAFC binder-free cathode. The excellent NO3RR performance was attributed to the rational polymer tethering strategy for the binder-free cathode construction. The introduction of polyacrylonitrile for electrospinning shaping essentially regulated the structural and compositional distribution of binder-free electrode during followed pyrolysis. The in-situ infrared spectroscopy and DFT calculation demonstrated that the Fe and Co regulation optimized the adsorption energy of key intermediate products with suppressing the side reactions. The bimetal binder-free cathode offers a promising strategy for selective and effective electroreduction of nitrate for ammonia synthesis.

Improved chloralkaline reversible electrochemical cells featuring a catalytic-coating-free 3-D printed titanium gas diffusion electrode

This study presents a novel resin 3-D printed chloralkaline reversible electrochemical cell featuring a 3-D printed titanium (3DP-Ti) cathode and a mixed-metal oxide anode. It evaluates the capability of this cell for electricity production (using hydrogen and bleach as fuel and comburent, respectively) and electrolysis of NaCl brine (producing hydrogen, chlorine, and retaining carbon dioxide). Parameters including NaCl concentration, bleach pH, and temperature were varied for examination. Despite the assembled 3DP-Ti does not contain any cathodic catalytic layer, the cell shows outstanding performance and it reaches maximum power densities of 7.38 mWcm−2 and maximum current densities of 12.7 mAcm−2. Hydrogen is flowed through small pores and electricity production dependence on feeding solution pH, electrolyte concentration, and temperature are observed. The system proved as a reversible chloralkaline electrochemical cell by confirming its good performance as an electrolyzer, with faradic efficiencies of 100 % for hydrogen production and 70 % for chlorine production. Energy efficiencies reached 196.54 mg Cl2/Wh and 7.48 mg H2/Wh. During operation as an electrolyzer (stream feeding to the gas diffusion cathode), it also demonstrated the capacity to fix carbon dioxide contained in gaseous streams by reacting with hydroxyl ions produced during the electrochemical hydrogen production. The fixation efficiency was 220.0 mg CO2 fixed/Wh. These findings demonstrate progress in electrochemical cell technology, highlighting its potential for various electrochemical applications.

Modulating local environment for electrocatalytic CO2 reduction to alcohol

The fundamental drivers for the selective CO2 electroreduction reaction (CO2RR) to alcohol (e.g. C2H5OH) or alkene (e.g. C2H4) still remain unexplored. Previous studies mainly focus on catalyst engineering to enhance electrocatalytic performance, while the selectivity to alcohol has reached a bottleneck. Here, we modulate local environment to reveal the contribution of *CO and *H reaction intermediates in the selectivity of CO2 to alcohol/alkene on Cu electrocatalyst. Through modifications on local CO2 concentration, varied *CO/*H coverage ratios can be achieved. Based on the reaction kinetics analysis, we find that there is a direct connection between local CO2 concentration and interfacial *CO and *H coverage, which finally affects the selectivity of CO2 to alcohol or alkene. To verify this principle, polyvinylidene fluoride (PVDF), a hydrophobic binder, were selected and introduced into the catalyst surface for further enhancement of interfacial *CO/*H coverage. With PVDF decoration, alcohol/alkene ratio increased from 0.69 to 1.35. The Faradic Efficiency of alcohol is up to 37.5 % under a high current density of 800 mA cm–2 (a partial current density of 300 mA cm–2), surpassing most reported Cu-based materials. Our findings provide a fundamental guidance for CO2RR to alcohol under an industrial-level current density.

Fe‐doped Ni3S2@CoSx nanoarrays derived from MOF as bifunctional electrocatalysts for efficient overall water‐splitting

AbstractBACKGROUNDFabricating high‐performance bifunctional electrocatalysts remains challenging to promote the development of electrocatalytic water‐splitting.RESULTA heterostructure Fe‐Ni3S2@CoSx/NF was successfully synthesized using an interfacial engineering strategy. Benefiting from the strong synergistic effect between highly active cobalt sulfide (CoSx) and iron‐doped trinickel‐disulfide (Ni3S2) (Fe‐Ni3S2), Fe‐Ni3S2@CoSx/NF exhibited outstanding bifunctional performance, with low overpotentials of 77 and 217 mV for the cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER), respectively, at 10 mA cm−2.CONCLUSIONThe CoSx nanoarrays and Fe‐Ni3S2 nanosheets respectively served as HER and OER active centers. When Fe‐Ni3S2@CoSx/NF was used as both cathode and anode for overall water‐splitting, a low voltage of 1.52 V was required to reach the current density of 10 mA cm−2 with nearly 100% Faradic efficiency and outstanding durability. © 2024 Society of Chemical Industry (SCI).

Enzymatic Mesoporous Metal Nanocavities for Concurrent Electrocatalysis of Nitrate to Ammonia Coupled with Polyethylene Terephthalate Upcycling.

Electrochemical upcycling of waste pollutants into high value-added fuels and/or chemicals is recognized as a green and sustainable solution that can address the resource utilization on earth. Despite great efforts, their progress has seriously been hindered by the lack of high-performance electrocatalysts. In this work, bimetallic PdCu mesoporous nanocavities (MCs) are reported as a new bifunctional enzymatic electrocatalyst that realizes concurrent electrocatalytic upcycling of nitrate wastewater and polyethylene terephthalate (PET) plastic waste. Abundant metal mesopores and open nanocavities of PdCu MCs provide the enzymatic confinement of key intermediates for the deeper electroreduction of nitrate and accelerate the transport of reactants/products within/out of electrocatalyst, thus affording high ammonia Faradic efficiency (FENH3) of 96.6% and yield rate of 5.6mgh-1mg-1 at the cathode. Meanwhile, PdCu MC nanozymes trigger the selective electrooxidation of PET-derived ethylene glycol (EG) into glycolic acid (GA) and formic acid with high FEs of >90% by a facile regulation of potentials at the anode. Moreover, concurrent electrosynthesis of value-added NH3 and GA is disclosed in the two-electrode coupling system, further confirming the high efficiency of bifunctional PdCu MC nanozymes in producing value-added fuels and chemicals from waste pollutants in a sustainable manner.

Sulfidation-Induced Surface Local Electronic and Atomic Structures in a Silver Catalyst Enables Silicon Photocathode for Selective and Efficient Photoelectrochemical CO2 Reduction.

Converting CO2 to value-added chemicals through a photoelectrochemical (PEC) system is a creative approach toward renewable energy utilization and storage. However, the rational design of appropriate catalysts while being effectively integrated with semiconductor photoelectrodes remains a considerable challenge for achieving single-carbon products with high efficiency. Herein, we demonstrate a novel sulfidation-induced strategy for in situ grown sulfide-derived Ag nanowires on a Si photocathode (denoted as SD-Ag/Si) based on the standard crystalline Si solar cells. Such an exquisite design of the SD-Ag/Si photocathode not only provides a large electrochemically active surface area but also endows abundant active sites of Ag2S/Ag interfaces and high-index Ag facets for PEC CO production. The optimized SD-Ag/Si photocathode displays an ideal CO Faradic efficiency of 95.2% and an onset potential of +0.26 V versus the reversible hydrogen electrode, ascribed to the sulfidation-induced synergistic effect of the surface atomic arrangement and electronic structure in Ag catalysts that promote charge transfer, facilitate CO2 adsorption and activation, and suppress hydrogen evolution reaction. This sulfidation-induced strategy represents a scalable approach for designing high-performance catalysts for electrochemical and PEC devices with efficient CO2 utilization.

Electrosynthesis of nitrate by FeS2-TiO2 heterogeneous nanoparticles supported on 2-methylimidazolium functionalized polypyrrole/graphene oxide

Electrochemical nitrogen oxidation reaction (NOR) acts as a clean and sustainable approach for promisingly replacing the conventional industrial method for producing nitrate. Designing and preparing the effective electrocatalysts for NOR has aroused great research interests. Herein, FeS2-TiO2 heterostructures are well-dispersed on the surface of 2-methylimidazolium functionalized polypyrrole/graphene oxide (2-MeIm/PPy/GO) by the in situ growth due to the ion-exchange and the coordination between the 2-MeIm groups and the metal precursors, which exhibit the excellent NOR electroactivity. The highest NO3– yield by the obtained FeS2-TiO2@2-MeIm/PPy/GO reaches to 137.04 μg h−1 mg-1act. with the maximum Faradic efficiency (FE) of 4.38 % at 2.04 V (vs. RHE), better than most reported electrocatalysts. The good selectivity for producing nitrate is also achieved, but the stability of both the NO3– yield and FE present a trend of rising and then declining in the cyclic test of FeS2-TiO2@2-MeIm/PPy/GO. The irreversible conversion of the electrocatalysts can be confirmed through detailed characterization towards the crystal structures and chemical states of FeS2-TiO2@2-MeIm/PPy/GO after long term NOR test. The electrochemical step of NOR mainly occurs at FeS2, converting the inert N2 to active *NO intermediates. SO42- generated at high NOR potential gradually increase by the oxidation of S element, which can cause the promotion of the NOR performance before the fourth cycle. But along with the disappearance of FeS2 phase, FeS2-TiO2 as the catalytic center is finally irreversibly converted to Fe and S ions doped TiO2, resulting in the sharp drop of both the NO3– yield and FE at the sixth cycle. This work will provide valuable guidance for the designing and preparing NOR electrocatalysts.

Gray mesoporous SnO2 catalyst for CO2 electroreduction with high partial current density and formate selectivity

The mesoporous metal oxide semiconductors exhibit unique chemical and physical characteristics, making them highly desirable for catalysis, electrochemistry, energy conversion, and energy storage applications. Here, we report the facial fabrication of mesoporous gray SnO2 (MGS) electrocatalysts employing an evaporation-induced co-assembly (EICA) approach, utilizing poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) triblock copolymers Pluronic P123 (PEO-PPO-PEO) triblock copolymer as a template for electrochemical CO2 reduction reaction (eCO2RR). By sustaining the co-assembly conditions and utilizing a thermal treatment technique based on carbon, gray mesoporous SnO2 materials with a high density of active sites and oxygen vacancies can be constructed. The MGS materials were employed in eCO2RR in a flow cell type, which exhibits excellent catalytic activity and selectivity toward formate with a high partial current density of −234 mA cm−2 and Faradaic efficiency (FE) of 93.60 % at −1.3 V vs. reversible hydrogen electrode (RHE). Interestingly, the mesoporous SnO2 with a 1.5 wt% ratio of Sn precursor to P123 surfactant (MS-1.5@350N-400A) electrode exhibits a high level of Faradaic efficiency (FE) of (98%) at a low overpotential of −0.6 VRHE, which is a seldom recorded performance for similar systems. A stable FE of 96 ± 1% was observed in the range of −0.6 to −1.2 VRHE, which is the result of a large surface area (184 m2/g) and a high number of active sites and oxygen vacancies within the mesostructured framework.

Unlocking sustainable nitrate reduction: Earth-abundant bimetallic electrodes under galvanostatic evaluation

Electrochemical reduction of nitrate (ERN) has emerged as a green alternative to alleviate the NH3 production via the Haber-Bosch process. Harnessing earth-abundant materials for electrocatalysts is a logical strategy, minimizing dependence on the cost-prohibitive platinum group elements. While previous research has delved into the preparation and evaluation of electrodes for NH3 generation, much of it has been mainly focused on potentiostatic conditions and mechanisms elucidation, overlooking real-world scenarios and precluding the advancement towards technology implementation. This study addresses this gap by screening the performance of earth-abundant bimetallic electrodes, leveraging Cu foam as a substrate and modifying it with Cu2O, Ni(OH)2, SnO2, and Co(OH)x through electrodeposition. A comprehensive characterization encompassing morphological, structural, and electrochemical analysis was performed on the novel bimetallic surfaces. Electrolysis experiments targeting 30 mg L−1 NO3−-N were conducted under galvanostatic conditions (2.5, 5, 10, 20, and 40 mA cm−2), revealing the following trend in NH3 yield (mmol NH3 gcat−1 h−1): Cu/Co(OH)x > Cu/Cu2O > Cu foam > Cu/SnO2 > Cu/Ni(OH)2. Engineering figures of merit required for techno-economic analysis, such as Faradic efficiency, electrical energy per order, kinetic constants, and NH3 generation efficiency, were estimated for each configuration. This study not only sheds light on the operational conditions of ERN but also offers a roadmap toward sustainable and economically viable NH3 production.

Activating *CO by Strengthening Fe–CO π‐Backbonding to Enhance Two‐Carbon Products Formation toward CO2 Electroreduction on Fe–N4 Sites

AbstractMany non‐precious metal‐nitrogen (M–Nx)‐containing catalysts are highly efficient for electrochemical reduction of CO2 to CO and yet encounter challenges in further converting CO to more valuable two‐carbon products (C2), such as ethanol and acetic acid. The ambiguous structure‐activity relationship of the M–Nx moieties toward CO2 reduction reaction (CO2RR) results in difficulties in regulating the CO2RR product selectivity on the M–Nx‐containing catalysts. Herein, by using fluorinated iron phthalocyanines with axial‐coordinated ligands (L–FePc–F) as an M–N4‐based model electrocatalyst for CO2RR, a correlation between the electronic structure and C2 selectivity of Fe–N4 is revealed and a comprehensive descriptor based on the Fe–CO π‐backbonding is proposed for guiding the regulation of M–N4 toward higher C2 selectivity. Based on the regulation principle, the Br‐axial‐coordinated FePc–F (Br–FePc–F) remarkably increases the Faradic efficiency (FE) of C2 products from 0% (i.e., the FEC2 of FePc–F) to 34% due to the strengthened Fe–CO π‐backbonding stemming from the elevated 3dxz/dyz orbital energy and enhanced electron‐donating ability of the Fe centers of Fe–N4. This work provides a strategy and mechanism insights on the regulation of the C2 selectivity of CO2RR on the Fe–N4 moieties, which may be inspiring for precise construction and regulation of the M–Nx‐containing catalysts for specific CO2RR products.

Elaborate Modulating Binding Strength of Intermediates via Three-component Covalent Organic Frameworks for CO2 Reduction Reaction.

The catalytic performance for electrocatalytic CO2 reduction reaction (CO2RR) depends on the binding strength of the reactants and intermediates. Covalent organic frameworks (COFs) have been adopted to catalyze CO2RR, and their binding abilities are tuned via constructing donor-acceptor (DA) systems. However, most DA COFs have single donor and acceptor units, which caused wide-range but lacking accuracy in modulating the binding strength of intermediates. More elaborate regulation of the interactions with intermediates are necessary and challenge to construct high-efficiency catalysts. Herein, the three-component COF with D-A-A units was first constructed by introducing electron-rich diarylamine unit, electron-deficient benzothiazole and Co-porphyrin units. Compared with two-component COFs, the designed COF exhibit elevated electronic conductivity, enhanced reducibility, high efficiency charge transfer, further improving the electrocatalytic CO2RR performance with the faradic efficiency of 97.2 % at -0.8 V and high activity with the partial current density of 27.85 mA cm-2 at -1.0 V which exceed other two-component COFs. Theoretical calculations demonstrate that catalytic sites in three-component COF have suitable binding ability of the intermediates, which are benefit for formation of *COOH and desorption of *CO. This work offers valuable insights for the advancement of multi-component COFs, enabling modulated charge transfer to improve the CO2RR activity.

Elaborate Modulating Binding Strength of Intermediates via Three‐component Covalent Organic Frameworks for CO2Reduction Reaction

AbstractThe catalytic performance for electrocatalytic CO2reduction reaction (CO2RR) depends on the binding strength of the reactants and intermediates. Covalent organic frameworks (COFs) have been adopted to catalyze CO2RR, and their binding abilities are tuned via constructing donor‐acceptor (DA) systems. However, most DA COFs have single donor and acceptor units, which caused wide‐range but lacking accuracy in modulating the binding strength of intermediates. More elaborate regulation of the interactions with intermediates are necessary and challenge to construct high‐efficiency catalysts. Herein, the three‐component COF with D‐A‐A units was first constructed by introducing electron‐rich diarylamine unit, electron‐deficient benzothiazole and Co‐porphyrin units. Compared with two‐component COFs, the designed COF exhibit elevated electronic conductivity, enhanced reducibility, high efficiency charge transfer, further improving the electrocatalytic CO2RR performance with the faradic efficiency of 97.2 % at −0.8 V and high activity with the partial current density of 27.85 mA cm−2at −1.0 V which exceed other two‐component COFs. Theoretical calculations demonstrate that catalytic sites in three‐component COF have suitable binding ability of the intermediates, which are benefit for formation of *COOH and desorption of *CO. This work offers valuable insights for the advancement of multi‐component COFs, enabling modulated charge transfer to improve the CO2RR activity.

Efficient bubble/precipitate traffic enables stable seawater reduction electrocatalysis at industrial-level current densities

Seawater electroreduction is attractive for future H2 production and intermittent energy storage, which has been hindered by aggressive Mg2+/Ca2+ precipitation at cathodes and consequent poor stability. Here we present a vital microscopic bubble/precipitate traffic system (MBPTS) by constructing honeycomb-type 3D cathodes for robust anti-precipitation seawater reduction (SR), which massively/uniformly release small-sized H2 bubbles to almost every corner of the cathode to repel Mg2+/Ca2+ precipitates without a break. Noticeably, the optimal cathode with built-in MBPTS not only enables state-of-the-art alkaline SR performance (1000-h stable operation at –1 A cm−2) but also is highly specialized in catalytically splitting natural seawater into H2 with the greatest anti-precipitation ability. Low precipitation amounts after prolonged tests under large current densities reflect genuine efficacy by our MBPTS. Additionally, a flow-type electrolyzer based on our optimal cathode stably functions at industrially-relevant 500 mA cm−2 for 150 h in natural seawater while unwaveringly sustaining near-100% H2 Faradic efficiency. Note that the estimated price (~1.8 US$/kgH2) is even cheaper than the US Department of Energy’s goal price (2 US$/kgH2).

Cr2O3 promotes the catalytic performance of Bi-based catalysts for electrochemical CO2 reduction to HCOOH

Electrochemical CO2 reduction reaction (CO2RR) to formic acid is a much-anticipated way of converting excess CO2 to high-value-added products. Bismuth (Bi)-based materials are promising catalysts, but remain challenging in terms of activity and selectivity. Herein, we reported a composition manipulation strategy to achieve simultaneous high activity and selectivity for CO2RR towards formate by incorporating Lewis acid Cr2O3 into Bi. Specifically, a novel Bi-Cr2O3 crystalline-amorphous catalyst was prepared by electroreduction of bismuth chromate (Bi2(CrO4)3). The as-prepared catalyst shows nano-dendrites structure, promising the maximum exposure of active sites. The obtained Bi-Cr2O3 catalyst exhibits a high Faradic efficiency (FEformate, 93.3 %) at −1.1 V vs reversible hydrogen electrode (RHE), and can achieve a remarkable current density of −40.7 mA cm−2 at the same potential. Meanwhile, the FEformate remains above 90 % over a wide potential window (−0.8 ∼ −1.2 V vs RHE) and the stability can maintain for 13 h at −0.9 V vs RHE with high selectivity (>90 %) and stable physical phase. Furthermore, the Zn-CO2 battery assembled with a Bi-Cr2O3 catalyst achieves the greatest power density of 4.63 mW cm−2 and could maintain cyclic charge/discharge stability for 40 h.

Polyoxometalate-Intercalated Tremella-Like CoNi-LDH Nanocomposites for Electrocatalytic Nitrite-Ammonia Conversion.

The electrocatalytic reduction of NO2- (NO2RR) holds promise as a sustainable pathway to both promoting the development of emerging NH3 economies and allowing the closing of the NOx loop. Highly efficient electrocatalysts that could facilitate this complex six-electron transfer process are urgently desired. Herein, tremella-like CoNi-LDH intercalated by cyclic polyoxometalate (POM) anion P8W48 (P8W48/CoNi-LDH) prepared by a simple two-step hydrothermal-exfoliation assembly method is proposed as an effective electrocatalyst for NO2- to NH3 conversion. The introduction of POM with excellent redox ability tremendously increased the electrocatalytic performance of CoNi-LDH in the NO2RR process, causing P8W48/CoNi-LDH to exhibit large NH3 yield of 0.369 mmol h-1 mgcat-1 and exceptionally high Faradic efficiency of 97.0% at -1.3 V vs the Ag/AgCl reference electrode in 0.1 M phosphate buffer saline (PBS, pH = 7) containing 0.1 M NO2-. Furthermore, P8W48/CoNi-LDH demonstrated excellent durability during cyclic electrolysis. This work provides a new reference for the application of POM-based nanocomposites in the electrochemical reduction of NO2- to obtain value-added NH3.

Methanol‐Facilitated Surface Reconstruction Catalysts for Near 200% Faradaic Efficiency in a Coupled System

AbstractThe coupling of the carbon dioxide reduction reaction (CO2RR) and methanol oxidation reaction (MOR) holds great promise for the energy‐efficient production of HCOO−. However, anode catalysts' limited selectivity (<80%) and stability (<15 h) have impeded electron utilization and HCOO− production rates. To overcome it, copper‐copper(I) oxide‐copper(II) oxide nanowires (Cu─CuO─Cu2O NWs) catalysts have been developed, which exhibit exceptional performance in promoting the MOR with a faradic efficiency of nearly 100% at commercially viable current densities, and long stability over 100 h at 100 mA cm−2. Interestingly, the unique structure of the catalysts, when exposed to methanol, facilitates a transition from Cu/CuO to Cu2O. This phenomenon promotes the MOR while inhibiting the competitive oxygen evolution reaction (OER). By coupling the anodic reaction with cathodic CO2 reduction, the system demonstrates exceptional performance in HCOO− production, achieving an overall faradic efficiency of nearly 200% at 100 mA cm−2 with a low cell voltage of 2.382 V. Techno‐economic analysis indicates that the production costs of HCOOH are ≈US$0.37 and 0.35 kg−1 at 100 and 150 mA cm−2, respectively, significantly lower than those associated with traditional electrochemical methods.

Ladder type covalent organic frameworks constructed with natural units for the oxygen and carbon dioxide reduction reactions

Covalent organic frameworks (COFs) constructed with metallocyclophane units and organic linkers have found application as electrocatalytic systems. Nevertheless, the majority of linkers within COFs necessitate intricate design and synthesis. Conversely, the potential utilization of natural building blocks in COF construction remains largely unexplored. In this study, we constructed a natural COF (CoPc-EA-COF) by employing a natural phenolic molecule (ellagic acid (EA)) as the linker and Co-hexadecafluorophthalocyanine (CoPc) as blocks. This framework serves as an electrocatalyst for both the oxygen reduction reaction (ORR) and carbon dioxide reduction reaction (CO2RR). The incorporation of EA units imparts the CoPc-EA-COF with elevated electronic conductivity, enhanced CO2 binding affinity, and superior reductive capacity compared to the controlled COF lacking EA units. The CoPc-EA-COF demonstrated enhanced performance in the ORR, as evidenced by a half-wave potential of 0.80 V. Moreover, it showcased elevated activity and selectivity in the CO2RR, achieving a maximum CO faradic efficiency of 97.32 % at − 0.8 V, along with turnover frequency (TOF) values reaching 2092 h−1. Theoretical calculations revealed that the presence of EA units facilitated the generation of OOH* and COOH* species, which are pivotal in the rate-determining stages of both ORR and CO2RR processes. The contribution of EA units significantly bolstered the overall catalytic activity.

Interface Engineering Overall Seawater Splitting of Self-Supporting CeOx@NiCo2O4 Arrays.

Exploring advanced electrocatalysts for overall seawater splitting is of great significance for large-scale green hydrogen production in which interface engineering has been considered as an effective strategy to enhance the intrinsic activities of the electrocatalysts. In this work, CeOx-modified NiCo2O4 nanoneedle arrays are designed and constructed in situ grown on Ni foam (NF) through a facile two-step synthesis method. Density functional theory calculations reveal that the strong interaction between CeOx and NiCo2O4 can regulate the electronic states of metal surfaces and optimize the electronic structures of the materials, essentially improving the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) properties. Specifically, in alkaline electrolytes, CeOx@NiCo2O4/NF exhibits superior electrocatalytic activities and stabilities, requiring overpotentials of 238 mV for the OER and 144 mV for the HER to achieve a current density of 10 mA cm-2. When applied to a simulated seawater splitting device, the CeOx@NiCo2O4/NF also maintains a battery voltage of 1.66 V to reach 10 mA cm-2 and exhibits good stability for over 60 h, with high faradic efficiencies (FEs) close to 100% for both the OER and HER.

Selective Electrified Propylene-to-Propylene Glycol Oxidation on Activated Rh-Doped Pd.

Renewable-energy-powered electrosynthesis has the potential to contribute to decarbonizing the production of propylene glycol, a chemical that is used currently in the manufacture of polyesters and antifreeze and has a high carbon intensity. Unfortunately, to date, the electrooxidation of propylene under ambient conditions has suffered from a wide product distribution, leading to a low faradic efficiency toward the desired propylene glycol. We undertook mechanistic investigations and found that the reconstruction of Pd to PdO occurs, followed by hydroxide formation under anodic bias. The formation of this metastable hydroxide layer arrests the progressive dissolution of Pd in a locally acidic environment, increases the activity, and steers the reaction pathway toward propylene glycol. Rh-doped Pd further improves propylene glycol selectivity. Density functional theory (DFT) suggests that the Rh dopant lowers the energy associated with the production of the final intermediate in propylene glycol formation and renders the desorption step spontaneous, a concept consistent with experimental studies. We report a 75% faradic efficiency toward propylene glycol maintained over 100 h of operation.

Sulphide induced highly selective electrocatalytic nitrobenzene reduction by Cu-doped 1T-MoS2

An electrocatalysis system with lower overpotential, higher Faradic efficiency and good product selectivity is highly desirable for the electroreduction of nitrobenzene (NB). Here, Metallic Cu-doped 1T-MoS2 with different Cu content were load onto a Ti mesh by using a one-step solvothermal method. The doping of Cu into 1T MoS2 can significantly enlarge the electrochemical surface area and decease the charge transfer resistance. Detailed electrochemical studies indicate the reduction of NB follows first-order kinetics with respect to NB and second-order regarding S2−. Thus, introduction of small amount of sulphide ions can significantly accelerate the reaction and further decrease the charge transfer resistance. As a result, 8 % Cu-MoS2 attains 97 % selectivity towards aniline with 76 % Faradaic efficiency (FE). Besides, 8 % Cu-MoS2 demonstrates good stability and retains its 92 % selectivity of aniline after 5 cycles. This work provides valuable insights into organic transformations using the tuned electronic structure of 1T-MoS2 via doping strategy.