The Controllable Reconstruction of Bi-MOFs for Electrochemical CO Reduction through Electrolyte and Potential Mediation.

Monitoring and controlling the reconstruction of materials under working conditions is crucial for the precise identification of active sites, elucidation of reaction mechanisms, and rational design of advanced catalysts. Herein, a Bi-based metal-organic framework (Bi-MOF) for electrochemical CO reduction is selected as a case study. In situ Raman spectra combined with ex situ electron microscopy reveal that the intricate reconstruction of the Bi-MOF can be controlled using two steps: 1) electrolyte-mediated dissociation and conversion of Bi-MOF to Bi O CO , and 2) potential-mediated reduction of Bi O CO to Bi.

Stable and Highly Efficient Hydrogen Evolution from Seawater Enabled by an Unsaturated Nickel Surface Nitride.

Electrocatalytic production of hydrogen from seawater provides a route to low-cost and clean energy conversion. However, the hydrogen evolution reaction (HER) using seawater is greatly hindered by the lack of active and stable catalysts. Herein, an unsaturated nickel surface nitride (Ni-SN@C) catalyst that is active and stable for the HER in alkaline seawater is prepared.

Graphene-encapsulated nickel-copper bimetallic nanoparticle catalysts for electrochemical reduction of CO to CO.

Highly selective CO2 electroreduction to CO (∼90% faradaic efficiency) was achieved on NiCu0.25 bimetallic nanoparticle catalysts. By combining Synchrotron based X-ray absorption and in situ Raman spectroscopy studies, we found that there is a negative correlation between the Cu content in NiCux and CO selectivity due to redistribution of the 3d electrons.

Electrochemical Reduction of CO to Ethane through Stabilization of an Ethoxy Intermediate.

Electrochemical conversion of CO into ethane is seldom observed because of the generally higher selectivity towards methane, ethylene, and ethanol. Consequently, little experimental evidence for its reaction mechanism exists and thus remains largely unknown. Now, by combining electrochemistry with in situ X-ray absorption fine-structure and in situ Raman techniques, iodide-derived copper (ID-Cu) and oxide-derived copper (OD-Cu) systems were studied to obtain a deeper understanding of the CO to ethane mechanism.

The Ampoule Method: A Pathway towards Controllable Synthesis of Electrocatalysts for Water Electrolysis.

The ampoule method provides a promising pathway towards the controllable synthesis of novel electrocatalysts for water electrolysis due to its straightforward manipulation of reaction conditions, accessible experimental design, and controlled environment. This Concept introduces the development of the ampoule method and anticipates its application in electrocatalyst synthesis for water electrolysis. First, the history, device configuration, and merits of the ampoule method are briefly introduced.

Contemporaneous oxidation state manipulation to accelerate intermediate desorption for overall water electrolysis.

Contemporaneous oxidation state engineering of Co, N and S for cobalt nitride and sulfide electrocatalysts is demonstrated to facilitate intermediate desorption for both the oxygen evolution reaction and the hydrogen evolution reaction, leading to efficient overall water electrolysis in a neutral buffer electrolyte.

Non-metal Single-Iodine-Atom Electrocatalysts for the Hydrogen Evolution Reaction.

Common-metal-based single-atom catalysts (SACs) are quite difficult to design due to the complex synthesis processes required. Herein, we report a single-atom nickel iodide (SANi-I) electrocatalyst with atomically dispersed non-metal iodine atoms. The SANi-I is prepared via a simple calcination step in a vacuum-sealed ampoule and subsequent cyclic voltammetry activation.

Graphitic Carbon Nitride (g-C N )-Derived N-Rich Graphene with Tuneable Interlayer Distance as a High-Rate Anode for Sodium-Ion Batteries.

Heteroatom-doped carbon materials with expanded interlayer distance have been widely studied as anodes for sodium-ion batteries (SIBs). However, it remains unexplored to further enlarge the interlayer spacing and reveal the influence of heteroatom doping on carbon nanostructures for developing more efficient SIB anode materials. Here, a series of N-rich few-layer graphene (N-FLG) with tuneable interlayer distance ranging from 0.

Understanding the Roadmap for Electrochemical Reduction of CO to Multi-Carbon Oxygenates and Hydrocarbons on Copper-Based Catalysts.

Electrochemical reduction of CO to high-energy-density oxygenates and hydrocarbons beyond CO is important for long-term and large-scale renewable energy storage. However, the key step of the C-C bond formation needed for the generation of C products induces an additional barrier on the reaction. This inevitably creates larger overpotentials and greater variety of products as compared to the conversion of CO to C products.

Single-Crystal Nitrogen-Rich Two-Dimensional MoN Nanosheets for Efficient and Stable Seawater Splitting.

Transition metal nitrides (TMNs) have great potential for energy-related electrocatalysis because of their inherent electronic properties. However, incorporating nitrogen into a transition metal lattice is thermodynamically unfavorable, and therefore most of the developed TMNs are deficient in nitrogen. Consequently, these TMNs exhibit poor structural stability and unsatisfactory performance for electrocatalytic applications.

Nonlithium Metal-Sulfur Batteries: Steps Toward a Leap.

Present mobile devices, transportation tools, and renewable energy technologies are more dependent on newly developed battery chemistries than ever before. Intrinsic properties, such as safety, high energy density, and cheapness, are the main objectives of rechargeable batteries that have driven their overall technological progress over the past several decades. Unfortunately, it is extremely hard to achieve all these merits simultaneously at present.

Bronze alloys with tin surface sites for selective electrochemical reduction of CO.

Low concentration tin bronze alloys show high selectivity for CO2 electroreduction to CO, while high concentration tin bronze alloys show high selectivity for formate. The tin surface sites appear to control selectivity by influencing the binding characteristics toward the first reaction intermediate on copper-based alloys.

Electronic and Structural Engineering of Carbon-Based Metal-Free Electrocatalysts for Water Splitting.

Since first being reported as possible electrocatalysts to substitute platinum for the oxygen reduction reaction (ORR), carbon-based metal-free nanomaterials have been considered a class of promising low-cost materials for clean and sustainable energy-conversion reactions. However, beyond the ORR, the development of carbon-based catalysts for other electrocatalytic reactions is still limited. More importantly, the intrinsic activity of most carbon-based metal-free catalysts is inadequate compared to their metal-based counterparts.

An Earth-Abundant Catalyst-Based Seawater Photoelectrolysis System with 17.9% Solar-to-Hydrogen Efficiency.

The implementation of water splitting systems, powered by sustainable energy resources, appears to be an attractive strategy for producing high-purity H in the absence of the release of carbon dioxide (CO ). However, the high cost, impractical operating conditions, and unsatisfactory efficiency and stability of conventional methods restrain their large-scale development. Seawater covers 70% of the Earth's surface and is one of the most abundant natural resources on the planet.

Emerging Two-Dimensional Nanomaterials for Electrocatalysis.

Over the past few decades, the design and development of advanced electrocatalysts for efficient energy conversion technologies have been subjects of extensive study. With the discovery of graphene, two-dimensional (2D) nanomaterials have emerged as some of the most promising candidates for heterogeneous electrocatalysts due to their unique physical, chemical, and electronic properties. Here, we review 2D-nanomaterial-based electrocatalysts for selected electrocatalytic processes.

NiO as a Bifunctional Promoter for RuO toward Superior Overall Water Splitting.

Conventional development of nanomaterials for efficient electrocatalysis is largely based on performance-oriented trial-and-error/iterative approaches, while a rational design approach at the atomic/molecular level is yet to be found. Here, inspired by a fundamental understanding of the mechanism for both oxygen and hydrogen evolution half reactions (OER/HER), a unique strategy is presented to engineer RuO for superior alkaline water electrolysis through coupling with NiO as an efficient bifunctional promoter. Benefitting from desired potential-induced interfacial synergies, NiO-derived NiOOH improves the oxygen binding energy of RuO for enhanced OER, and NiO also promotes water dissociation for enhanced HER on RuO -derived Ru.

Free-standing single-crystalline NiFe-hydroxide nanoflake arrays: a self-activated and robust electrocatalyst for oxygen evolution.

Free-standing single-crystalline NiFe-hydroxide nanoflake arrays grown in situ on nickel foam are synthesized using a simple hydrothermal method and they exhibit remarkable activity and durability for oxygen evolution in 1.0 M KOH, achieving a decreased overpotential of 235 mV to produce 10 mA cm current density after long-term operation up to 100 h.

The Hydrogen Evolution Reaction in Alkaline Solution: From Theory, Single Crystal Models, to Practical Electrocatalysts.

The hydrogen evolution reaction (HER) is a fundamental process in electrocatalysis and plays an important role in energy conversion for the development of hydrogen-based energy sources. However, the considerably slow rate of the HER in alkaline conditions has hindered advances in water splitting techniques for high-purity hydrogen production. Differing from well documented acidic HER, the mechanistic aspects of alkaline HER are yet to be settled.

Identification of pH-dependent synergy on Ru/MoS interface: a comparison of alkaline and acidic hydrogen evolution.

Engineering bifunctional interfaces for enhanced alkaline hydrogen evolution reaction (HER) kinetics is achieved by rational coupling of Ru nanoparticles and defect-rich MoS nanosheets via a simple wet-chemical method. Comprehensive material characterizations, especially high-resolution transmission electron microscopy, reveal well-defined interfaces between both components, leading to interfacial synergy whereby Ru expedites water dissociation and nearby defect-rich MoS enables favorable hydrogen adsorption for recombination into H. The designed Ru/MoS material demonstrates remarkable catalytic activity towards alkaline HER (-13 mV at -10 mA cm) with stable operation after 12 h or 1000 cycles, which is superior to almost all Ru-based and MoS-based electrocatalysts and even outperforms commercial 20 wt% Pt/C at overpotentials larger than -78 mV in alkaline media.

Recent Advances in Atomic Metal Doping of Carbon-based Nanomaterials for Energy Conversion.

Nanostructured metal-contained catalysts are one of the most widely used types of catalysts applied to facilitate some of sluggish electrochemical reactions. However, the high activity of these catalysts cannot be sustained over a variety of pH ranges. In an effort to develop highly active and stable metal-contained catalysts, various approaches have been pursued with an emphasis on metal particle size reduction and doping on carbon-based supports.

Molecule-Level g-CN Coordinated Transition Metals as a New Class of Electrocatalysts for Oxygen Electrode Reactions.

Organometallic complexes with metal-nitrogen/carbon (M-N/C) coordination are the most important alternatives to precious metal catalysts for oxygen reduction and evolution reactions (ORR and OER) in energy conversion devices. Here, we designed and developed a range of molecule-level graphitic carbon nitride (g-CN) coordinated transition metals (M-CN) as a new generation of M-N/C catalysts for these oxygen electrode reactions. As a proof-of-concept example, we conducted theoretical evaluation and experimental validation on a cobalt-CN catalyst with a desired molecular configuration, which possesses comparable electrocatalytic activity to that of precious metal benchmarks for the ORR and OER in alkaline media.

Anion and Cation Modulation in Metal Compounds for Bifunctional Overall Water Splitting.

As substitutes for precious cathodic Pt/C and anodic IrO2 in electrolytic water splitting cells, a bifunctional catalyst electrode (Fe- and O-doped Co2P grown on nickel foam) has been fabricated by manipulating the cations and anions of metal compounds. The modified catalyst electrode exhibits both superior HER and OER performances with high activity, favorable kinetics, and outstanding durability. The overall ability toward water splitting is especially extraordinary, requiring a small overpotential of 333.

Size Fractionation of Two-Dimensional Sub-Nanometer Thin Manganese Dioxide Crystals towards Superior Urea Electrocatalytic Conversion.

A universal technique has been proposed to sort two-dimensional (2D) sub-nanometer thin crystals (manganese dioxide MnO2 and molybdenum disulfide MoS2 ) according to their lateral dimensions. This technique is based on tuning the zeta potential of their aqueous dispersions which induces the selective sedimentation of large-sized 2D crystals and leaves the small-sized counterparts in suspension. The electrocatalytic properties of as-obtained 2D ultrathin crystals are strongly dependent on their lateral size.

Three dimensional nitrogen-doped graphene hydrogels with in situ deposited cobalt phosphate nanoclusters for efficient oxygen evolution in a neutral electrolyte.

A hybrid electrode of cobalt phosphate (CoPi) on nitrogen doped graphene hydrogels was fabricated by hydrothermal treatment of graphene oxide followed by CoPi electrodeposited in situ, which showed excellent performance toward oxygen reaction in a neutral electrolyte.