Lattice‐Matching Formed Mesoporous Transition Metal Oxide Heterostructures Advance Water Splitting by Active Fe–O–Cu Bridges

Abstract

carbon-intensive fuels. Hydrogen represents a versatile fuel with high energy density and low carbon emission. In 2020, the global hydrogen generation market size was valued at ≈120 billion USD and is expected to rapidly expand. Presently, industrial hydrogen is primarily acquired from natural gas reforming that involves energy-consuming processes with extensive greenhouse gas release. Alternatively, electrochemical water splitting is a sustainable technique to store the intermittent electricity and produce high-purity hydrogen under ambient condition. [1] The water-splitting process consists of anodic oxygen evolution reaction (OER) and cathodic hydrogen evolution reaction (HER), in which electrocatalysts are particularly vital to lower their energy barriers and reduce the required overpotentials. [2] Currently, precious metal (e.g., Pt) and metal oxides (e.g., RuO 2 , and IrO 2 ) hold the benchmark performance toward HER and OER, respectively. [3] However, their nature scarcity and high cost considerably impede their widespread utilization. Therefore, it is desirable to develop costeffective OER/HER catalysts with active, abundant, and robust surface reactive sites. Non-precious transition metal-based materials, such as oxides, [4] sulfides, [5] LDHs, [6] MOFs, [7] and their composites, [8] have received intensive research in water splitting due to their tunable structure, stability, as well as high reserve. Strategies including morphology and components tuning are applied for advanced electrocatalysts. High material surface area and porosity benefit the intermediate accessibility and fast mass transport during the electrochemical reactions. Researchers pursuit improved electrocatalysis by fabricating porous or hierarchical catalysts with highly exposed reactive sites. [9] However, the synthesis of the highly porous transition metal catalysts with the controlled crystalline phase using the traditional template strategy often needs tedious and timeconsuming manufacturing. In addition, regarding the required bifunctionality (i.e., OER and HER) for water splitting, the integration of different nanostructures by heterostructure fabrication is adopted for further optimizing the electrocatalytic performance. The interface engineering and electronic regulation facilitate the optimized chemisorption of the reaction Developing efficient bifunctional electrocatalysts toward oxygen/hydrogen evolution reactions is crucial for electrochemical water splitting toward hydrogen production. The high-performance electrocatalysts depend on the catalytically active and highly accessible reaction sites and their structural robustness, while the rational design of such electrocatalysts with desired features avoiding tedious manufacture is still challenging. Here, a facile method is reported to synthesize mesoporous and heterostructured transition metal oxides strongly anchored on a nickel skeleton (MH-TMO) containing identified Fe-Cu oxide interfaces with high intrinsic activity, easy accessibility for reaction intermediates, ...

Hierarchical Ni(OH)2–MnO2hollow spheres as an electrode material for high-performance supercapacitors

“…Moreover, the interface area in the electrode can increase the active sites with unique electrochemical behaviors, thus affording an admirable electrochemical performance. 19,20,55 In short, benefiting from structural and compositional advantages, the hierarchical Ni(OH) 2 -MnO 2 hollow spheres are demonstrated to be a desirable candidate electrode material for supercapacitors.…”

Zinc‐ion hybrid supercapacitors: Design strategies, challenges, and perspectives

“…Numerous energy storage systems with superior electrochemical performance (long cycle stability and high energy density/power density) have emerged since the first commercialization of rechargeable lithium‐ion batteries in 1990, including sodium‐ion batteries, [ 1–3 ] lithium‐sulfur batteries, [ 4–6 ] aqueous batteries, [ 7,8 ] supercapacitors, [ 9,10 ] and so on. [ 11–16 ] Meanwhile, the batteries often have extremely high energy densities, but they have a short cycle life and safety risks due to severe redox reactions and dendritic complications. On the contrary, supercapacitors exhibit a higher power density and longer cycle life, owing to the fast and reversible ion adsorption/desorption at the electrode/electrolyte interface, whereas their energy density (5–10 Wh kg −1 ) is much lower than that of batteries.…”

Electronic modulation of cobalt–molybdenum oxideviaTe doping embedded in a carbon matrix for superior overall water splitting

“…[18][19][20][21] However, the development of TMOs is hindered because of the limited number of active sites and poor electrical conductivity. [22][23][24][25] In this regard, various emerging strategies have been employed to optimize the performance of TMO electrocatalysts, among which heteroatom doping is one of the main research areas. [26][27][28] Elemental doping as a facile technique effectively improves the electronic structure and the active area of TMOs to enhance their intrinsic activity.…”