Length-tunable Pd2Sn@Pt core-shell nanorods for enhanced ethanol electrooxidation with concurrent hydrogen production

Integration of Phosphorus in PdCr Metallene for Enhanced CO-Tolerant Alcohol Electrooxidation

Pd-based alloys are among the most attractive catalysts for direct alcohol fuel cells. However, their widespread use is limited by the high cost of Pd and their susceptibility to deactivation by surface-adsorbed reaction intermediates, particularly CO. In this study, we engineered an ultrathin 2D PdCr metallene to minimize Pd usage and doped it with phosphorus to enhance its CO tolerance. The resulting P-PdCr metallene demonstrated significantly higher activity, stability, and CO tolerance for the electrooxidation of various alcohols compared to PdCr metallene and commercial Pd/C catalysts. Particularly, for the methanol oxidation reaction (MOR), the P-PdCr catalyst achieved a mass activity of 2.64 A mg-1Pd and a specific activity of 5.81 mA cm-2, maintaining remarkable stability over a duration of 27 h. Density functional theory calculations revealed that the enhanced performance is attributed to the incorporation of Cr and P atoms into the Pd metallene structure. This incorporation significantly reduces the energy barriers of the potential-determining step in the MOR process, mitigates CO adsorption on the catalyst surface, and accelerates the conversion of reaction intermediates. The strategic doping of phosphorus into the metallene structure introduces a novel approach for developing Pd-based catalysts with enhanced CO tolerance in alcohol electrooxidation.

Hydrothermal nickel selenides as efficient electrodes in alkaline media: application to supercapacitors and the methanol oxidation reaction

The advancement of active electrochemical materials is pivotal for enhancing energy conversion and storage technologies, which is essential for a sustainable future. Furthermore, achieving cost-effective technologies necessitates avoiding the use of noble metals and low-throughput processes that require high vacuum or high temperatures. Herein, we describe in detail a simple solution-based protocol to obtain a series of phase-controlled nickel selenide nanomaterials. The electrochemical performance of these materials, influenced by the phase and morphology, has been further analyzed. To showcase the application of these materials, two technologies are considered: (i) supercapacitors; and (ii) the methanol oxidation reaction (MOR). In particular, the Ni3Se4-based electrode in 1 M KOH shows an initial specific capacitance of 1903.5 F g-1 at a discharge current of 0.1 mA and displays a notable stability for over 3000 cycles. Furthermore, in an alkaline medium with methanol, this electrode produces a current density of 95.5 mA cm-2, facilitating methanol-to-formate conversion with a faradaic efficiency of up to 95.7% during a continuous 20-hour test. This research underscores the potential of nickel selenide nanomaterials in driving the next generation of energy storage and conversion technologies.

Bifunctional PdMoPt trimetallene boosts alcohol-water electrolysis

Substituting oxygen evolution with alcohol oxidation is crucial for enhancing the cathodic hydrogen evolution reaction (HER) at low voltages. However, the development of high-performance bifunctional catalysts remains a challenge. In this study, an ultrathin and porous PdMoPt trimetallene is developed using a wet-chemical strategy. The synergetic effect between alloying metals regulates the adsorption energy of reaction intermediates, resulting in exceptional activity and stability for the electrooxidation of various alcohols. Specifically, the mass activity of PdMoPt trimetallene toward the electrooxidation of methanol, ethylene glycol, and glycerol reaches 6.13, 5.5, and 4.37 A mgPd+Pt -1, respectively. Moreover, the catalyst demonstrates outstanding HER activity, requiring only a 39 mV overpotential to achieve 10 mA cm-2. By employing PdMoPt trimetallene as both the anode and cathode catalyst, we established an alcohol-water hybrid electrolysis system, significantly reducing the voltage requirements for hydrogen production. This work presents a promising avenue for the development of bifunctional catalysts for energy-efficient hydrogen production.

Nickel foam supported Mn-doped NiFe-LDH nanosheet arrays as efficient bifunctional electrocatalysts for methanol oxidation and hydrogen evolution

Electrochemical upgrading methanol into value-added formate at the anode in alkaline media enables the boosting production of hydrogen fuel at the cathode with saved energy. To achieve such a cost-effective and efficient electrocatalytic process, herein this work presents a Mn-doped nickel iron layered double hydroxides supported on nickel foam, derived from a simple hydrothermal synthesis. This developed electrocatalyst could act as an efficient bifunctional electrocatalyst for methanol-to-formate with a high faradaic efficiency of nearly 100 %, and for hydrogen evolution reaction, at an external potential of 1.5 V versus reversible hydrogen electrode. Additionally, a current density of 131.1 mA cm-2 with a decay of merely 12.2 % over 120 h continuous long-term testing was generated in co-electrocatalysis of water/methanol solution. Further density functional theoretical calculations were used to unravel the methanol-to-formate reaction mechanism arising from the doping of Fe and/or Mn. This work offers a good example of co-electrocatalysis to produce formate and green hydrogen fuel using a bifunctional electrocatalyst.

Strain and Shell Thickness Engineering in Pd3 Pb@Pt Bifunctional Electrocatalyst for Ethanol Upgrading Coupled with Hydrogen Production

The ethanol oxidation reaction (EOR) is an attractive alternative to the sluggish oxygen evolution reaction in electrochemical hydrogen evolution cells. However, the development of high-performance bifunctional electrocatalysts for both EOR and hydrogen evolution reaction (HER) is a major challenge. Herein, the synthesis of Pd3 Pb@Pt core-shell nanocubes with controlled shell thickness by Pt-seeded epitaxial growth on intermetallic Pd3 Pb cores is reported. The lattice mismatch between the Pd3 Pb core and the Pt shell leads to the expansion of the Pt lattice. The synergistic effects between the tensile strain and the core-shell structures result in excellent electrocatalytic performance of Pd3 Pb@Pt catalysts for both EOR and HER. In particular, Pd3 Pb@Pt with three Pt atomic layers shows a mass activity of 8.60 A mg-1 Pd+Pt for ethanol upgrading to acetic acid and close to 100% of Faradic efficiency for HER. An EOR/HER electrolysis system is assembled using Pd3 Pb@Pt for both the anode and cathode, and it is shown that low cell voltage of 0.75 V is required to reach a current density of 10 mA cm-2 . The present work offers a promising strategy for the development of bifunctional catalysts for hybrid electrocatalytic reactions and beyond.