Phytate-coordinated nickel foam with enriched NiOOH intermediates for 5-hydroxymethylfurfural electrooxidation

High voltage driven MnO2/CuO for efficient oxidation of 5-hydroxymethylfurfural

Electrocatalytic 5-hydroxymethylfurfural oxidation to 2,5-furandicarboxylic acid (FDCA) faces challenges like low efficiency at high voltage. This study fabricated MnO2/CuO, achieving 98.2% Faraday efficiency (72.12 mA cm-2) at 1.6 VRHE and 80.2% at 1.7 VRHE, which offers a novel approach for high-voltage FDCA production.

Large Organic Polar Molecules Tailored Electrode Interfaces for Stable Lithium Metal Battery

Lithium (Li) metal batteries (LMBs) are deemed as ones of the most promising energy storage devices for next electrification applications. However, the uneven Li electroplating process caused by the diffusion-limited Li+ transportation at the Li metal surface inherently promotes the formation of dendritic morphology and instable Li interphase, while the sluggish Li+ transfer kinetic can also cause lithiation-induced stress on the cathode materials suffering from serious structural stability. Herein, a novel electrolyte designing strategy is proposed to accelerate the Li+ transfer by introducing a trace of large organic polar molecules of lithium phytate (LP) without significantly altering the electrolyte structure. The LP molecules can afford a competitive solvent attraction mechanism against the solvated Li+, enhancing both the bulk and interfacial Li+ transfer kinetic, and creating better anode/cathode interfaces to suppress the side reactions, resulting in much improved cycling efficiency of LMBs. Using LP-based electrolyte, the performance of LMB pouch cell with a practical capacity of ~1.5 Ah can be improved greatly. This strategy opens up a novel electrolyte designing route for reliable LMBs.

Amorphous-crystalline heterostructure: Efficient catalyst for biomass oxidation coupled with hydrogen evolution

The development of catalysts with high activity, selectivity, and stability is critical for biomass upgrading coupled with hydrogen evolution. In this study, we present a simple method for fabricating crystalline-amorphous phase heterostructures using the etching effect of the acidic medium generated during cobalt salt hydrolysis, resulting in the formation of NiCo(OH)x-modified Ni/NiMoO4 nanosheets electrode (NiCo(OH)x/Ni/NiMoO4/NF). The nanosheets array formed during the synthesis process enlarges the surface area of the prepared catalyst, which facilitates the exposure of electrochemically active sites and improves mass transfer. Unexpectedly, the strong coupling interactions between the amorphous-crystalline heterointerface optimize the adsorption of reaction molecules and the corresponding charge transfer process, consequently boosting the catalytic activity for the 5-hydroxymethylfurfural oxidation reaction (HMFOR) and hydrogen evolution reaction (HER). Specifically, NiCo(OH)x/Ni/NiMoO4/NF catalyst requires only 1.34 V to obtain a current density of 10 mA cm-2 for HMFOR-coupled H2 evolution, and operates stably for 13 consecutive cycles with good product selectivity. This work thus provides insights into the design of efficient and robust catalysts for HMFOR-assisted H2 evolution.

Interfacial Micro-Environment of Electrocatalysis and Its Applications for Organic Electro-Oxidation Reaction

Conventional designing principal of electrocatalyst is focused on the electronic structure tuning, on which effectively promotes the electrocatalysis. However, as a typical kind of electrode-electrolyte interface reaction, the electrocatalysis performance is also closely dependent on the electrocatalyst interfacial micro-environment (IME), including pH, reactant concentration, electric field, surface geometry structure, hydrophilicity/hydrophobicity, etc. Recently, organic electro-oxidation reaction (OEOR), which simultaneously reduces the anodic polarization potential and produces value-added chemicals, has emerged as a competitive alternative to oxygen evolution reaction, and the role IME played in OEOR is receiving great interest. Thus, this article provides a timely review on IME and its applications toward OEOR. In this review, the IME for conventional gas-involving reactions, as a contrast, is first presented, and then the recent progresses of IME toward diverse typical OEOR are summarized; especially, some representative works are thoroughly discussed. Additionally, cutting-edge analytical methods and characterization techniques are introduced to comprehensively understand the role IME played in OEOR. In the last section, perspectives and challenges of IME regulation for OEOR are shared.

Electronic Modulation Induced by Ni-VN Heterojunction Reinforces Electrolytic Hydrogen Evolution Coupled with Biomass Upgrade

The renewable electricity-driven hydrogen evolution reaction (HER) coupled with biomass oxidation is a powerful avenue to maximize the energy efficiency and economic feedback, but challenging. Herein, porous Ni-VN heterojunction nanosheets on nickel foam (Ni-VN/NF) are constructed as a robust electrocatalyst to simultaneously catalyze HER and 5-hydroxymethylfurfural electrooxidation reaction (HMF EOR). Benefiting from the surface reconstruction of Ni-VN heterojunction during the oxidation process, the derived NiOOH-VN/NF energetically catalyzes HMF into 2,5-furandicarboxylic acid (FDCA), yielding the high HMF conversion (>99%), FDCA yield (99%), and Faradaic efficiency (>98%) at the lower oxidation potential along with the superior cycling stability. Ni-VN/NF is also surperactive for HER, exhibiting an onset potential of ≈0 mV and Tafel slope of 45 mV dec-1 . The integrated Ni-VN/NF||Ni-VN/NF configuration delivers a compelling cell voltage of 1.426 V at 10 mA cm-2 for the H2 O-HMF paired electrolysis, about 100 mV lower than that for water splitting. Theoretically, for Ni-VN/NF, the superiority in HMF EOR and HER is mainly dominated by the local electronic distribution at the heterogenous interface, which accelerates the charge transfer and optimize the adsorption of reactants/intermediates by modulating the d-band center, therefore being an advisable thermodynamic and kinetic process.

In Situ Fabrication of Mn-Doped NiMoO4 Rod-like Arrays as High Performance OER Electrocatalyst

The slow kinetics of the oxygen evolution reaction (OER) is one of the significant reasons limiting the development of electrochemical hydrolysis. Doping metallic elements and building layered structures have been considered effective strategies for improving the electrocatalytic performance of the materials. Herein, we report flower-like nanosheet arrays of Mn-doped-NiMoO₄/NF (where NF is nickel foam) on nickel foam by a two-step hydrothermal method and a one-step calcination method. The doping manganese metal ion not only modulated the morphologies of the nickel nanosheet but also altered the electronic structure of the nickel center, which could be the result of superior electrocatalytic performance. The Mn-doped-NiMoO₄/NF electrocatalysts obtained at the optimum reaction time and the optimum Mn doping showed excellent OER activity, requiring overpotentials of 236 mV and 309 mV to drive 10 mA cm^-2 (62 mV lower than the pure NiMoO₄/NF) and 50 mA cm^-2 current densities, respectively. Furthermore, the high catalytic activity was maintained after continuous operation at a current density of 10 mA cm^-2 of 76 h in 1 M KOH. This work provides a new method to construct a high-efficiency, low-cost, stable transition metal electrocatalyst for OER electrocatalysts by using a heteroatom doping strategy.

Etching-Induced Surface Reconstruction of NiMoO4 for Oxygen Evolution Reaction

Rational reconstruction of oxygen evolution reaction (OER) pre-catalysts and performance index of OER catalysts are crucial but still challenging for universal water electrolysis. Herein, we develop a double-cation etching strategy to tailor the electronic structure of NiMoO4, where the prepared NiMoO4 nanorods etched by H2O2 reconstruct their surface with abundant cation deficiencies and lattice distortion. Calculation results reveal that the double cation deficiencies can make the upshift of d-band center for Ni atoms and the active sites with better oxygen adsorption capacity. As a result, the optimized sample (NMO-30M) possesses an overpotential of 260 mV at 10 mA cm-2 and excellent long-term durability of 162 h. Importantly, in situ Raman test reveals the rapid formation of high-oxidation-state transition metal hydroxide species, which can further help to improve the catalytic activity of NiMoO4 in OER. This work highlights the influence of surface remodification and shed some light on activating catalysts.

A dual-functional Bi-doped Co3O4 nanosheet array towards high efficiency 5-hydroxymethylfurfural oxidation and hydrogen production

Here, we report that a Bi-doped Co₃O₄ nanosheet array grown on Ni foam can selectively catalyze HMF-to-FDCA oxidation at ambient conditions. The catalyst shows a faradaic efficiency of 97.7%, a yield rate of 362.5 μmol h^-1, and a conversion of nearly 100%, surpassing those of pristine Co₃O₄. Furthermore, when the catalyst was adopted as both the anode and cathode in a two-electrode system, H₂ and FDCA can be produced simultaneously.