Phosphorus incorporation accelerates ammonia electrosynthesis over a mesoporous Au film

Noncovalent composites of meso-substituted A2B2-porphyrins and carbon nanotubes for enhanced electrocatalytic oxygen reduction

Exploring highly active oxygen reduction electrocatalysts with low precious metals content is imperative but remains a considerable challenge. Herein, a series of heterobimetallic multi-walled carbon nanotubes (MWCNTs) electrocatalysts based on metal complexes are presented. These electrocatalysts feature diverse transition metals (M=Mn, Fe, Co, Ni) 5,15-bromophenyl-10, 20-methoxyphenyl porphyrin (MBMP) and tetrakis(triphenylphosphine)palladium (0) (Pd[P(Ph3)4]) anchored non-covalently on its surface. The resulting NiBMP-based MWCNTs with Pd[P(Ph3)4] (PdNiN4/MWCNTs) display outstanding electrocatalytic oxygen reduction activity (onset potential, 0.941 V; half wave potential, 0.830 V) and robust long-term durability in alkaline electrolyte. While in neutral condition, the MnBMP-based MWCNTs with Pd[P(Ph3)4] (PdMnN4/MWCNTs) are the most active heterobimetallic ORR catalyst and produce ultra-low concentration hydrogen peroxide (H2O2yield, 1.2%-1.3%). Synergistically tuning the ORR electrocatalytic activity and electron transfer pathway is achieved by the formation of NiBMP/MnBMP-Pd[P(Ph3)4] active sites. This work indicates such metalloporphyrin-Pd[P(Ph3)4] active sites on MWCNTs have significantly positive influence on electrocatalytic ORR systems and provides facile and mild strategy for designing highly efficient ORR electrocatalysts with ultra-low loading precious metal.

Interfacial engineering of hydrophobic octadecanethiol/Pd metallene toward electrocatalytic nitrogen reduction

In this work, we propose the modification of ultrathin and wrinkled Pd metallene by hydrophobic octadecanethiol (Pdene@C18) via Pd-S bonds for the nitrogen reduction reaction. The hydrophobic self-assembled monolayer C18 can effectively capture more N₂ and inhibit the hydrogen evolution reaction. As a result, a high NH₃ yield and Faraday efficiency of 27.97 μg h^-1 mg_cat.^-1 and 14.29% are achieved for Pdene@C18 under neutral conditions, respectively, highlighting the modification of hydrophobic monolayers for efficient nitrogen electro-reduction to ammonia.

Rare earth Y doping induced lattice strain of mesoporous PtPd nanospheres for alkaline oxygen reduction electrocatalysis

The synthesis of catalysts with controllable morphology and composition is important to enhance the catalytic performance for oxygen reduction reaction (ORR). Herein, trimetallic PtPdY mesoporous nanospheres (PtPdY MNs) are produced via a one-step chemical reduction method applying F127 as soft temple under acidic condition. The mesoporous structure provides a large contact area and also stimulates the diffusion and mass transfer of reactants and products. Besides, synergistic effect among Pt, Pd and Y elements effectively alters their electronic structure, enhancing the catalytic activity. Therefore, the PtPdY MNs show excellent ORR permanence to Pt/C under the alkaline solution. This study offers an effective channel for the preparation of mesoporous metals with rare earth metal doping towards promising electrocatalytic applications.

Rh metallene with functionalized polypyrrole surface for hydrogen evolution over a wide pH range

Interface engineering of two-dimensional (2D) materials by conductive polymer modification is one of the valid methods to promote hydrogen evolution reaction (HER) performance. Herein, we report a simple and universal strategy for the synthesis of polypyrrole (PPy) modified Rh metallene (Rh@PPy metallene) towards an efficient pH-universal HER. Due to the unique ultrathin 2D metallene structure and the optimized electronic structure between the metallene-PPy surfaces, the as-prepared Rh@PPy metallene not only exhibits excellent HER activity with low overpotentials of 16, 39 and 42 mV in 0.5 M H₂SO₄, 1 M KOH, and 1 M phosphate buffer solution at current density of 10 mA cm^-2, but also displays outstanding stability and durability. This work provides a well-founded pathway to constructe metallene-organic interfaces for various electrocatalytic applications.

Nitrogen-doped Ru film for energy-saving hydrogen production assisted with hydrazine oxidation

Herein, a universal approach is proposed to prepare a nitrogen-doped mesoporous Ru film with uniform pore size on nickel foam (N-mRu/NF) as an active bifunctional catalyst for energy-saving hydrogen production. The N-mRu/NF requires an ultrasmall overpotential of -60 and 62 mV to achieve 100 mA cm^-2 for the hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR), respectively. When used for HER-HzOR electrolysis, N-mRu/NF requires low voltages of 0.023 and 0.184 V at 10 and 100 mA cm^-2, respectively.

B, P-co-doped PdCu nanothorn assemblies for enhanced oxygen reduction electrolysis

Nonmetal doping is a promising strategy to improve electrocatalytic performance of noble metal based catalysts for oxygen reduction reaction (ORR). Herein, we report a facile method to fabricate PdCuBP nanothorn assemblies (PdCuBP NTAs) by co-doping B and P into pre-synthesized PdCu NTAs using NaBH₄and NaH₂PO₂as B source and P source, respectively. The metal-nonmetal structure and multi-branched morphology can optimize oxygen adsorption energy and avoid catalyst migration, agglomeration and Ostwald ripening. As such, the obtained PdCuBP NTAs exhibit efficient activity and excellent long-term stability for ORR. This research offers an excellent strategy for co-doping nonmetal elements into metal nanocrystals with controllable composition and structure to improve electrocatalytic ORR performance.

Heterogeneous Pd-PdO mesoporous film for ammonia electrosynthesis

Exploring cost-effective and highly active electrocatalysts is of great significance for sustainable electrochemical NH₃synthesis. Palladium (Pd)-based catalysts have been unanimously considered as one of the most efficient catalysts for the nitrogen reduction reaction (NRR). Herein, self-supported mesoporous Pd film with partial oxidation on Ni foam (mPd-PdO/NF) was synthesized through the micelle-assisted chemical replacement method coupled with air oxidation under 260 °C, and the mPd-PdO/NF electrocatalyst exhibited superior NRR performance with the maximum values ofr_NH3(24.8 mg h^-1mg_cat.^-1) and FE (16.64%) were obtained at -0.1 V, relative to the single counterparts (mPd/NF and mPdO/NF). It is proposed that both metallic Pd and its oxide domains when co-existing with a phase boundary between them can facilitate nitrogen activation and hydrogenation, resulting in an enhanced NRR performance. This work provides an inspiring strategy for the rational design of highly active and durable metal-metal-oxide nanoarchitectonics for ammonia electrosynthesis.

Tannic acid modified PdAu alloy nanowires as efficient oxygen reduction electrocatalysts

Design of the structure, composition and interface of the catalysts is very important to improve oxygen reduction reaction (ORR) catalytic activity under alkaline environment. Herein, we propose a direct method to rapid synthesis of tannic acid (TA) modified PdAu alloy nanowires (PdAu@TA NWs). Compared with pure PdAu NWs and commercial Pt/C, the PdAu@TA NWs exhibit superior ORR electrocatalytic activity (mass activity: 0.73 A mg^-1_metaland specific activity: 3.50 mA cm^-2), stability, and methanol tolerance in an alkaline medium because PdAu@TA NWs possess sufficient active sites and synergistic effect that can effectively promote the oxygen reduction, inhibit the oxidation of the catalyst and improve the methanol tolerance of the catalyst. This synthetic method is a promising strategy to prepare metallic catalyst with surface functionalization.