Tuning intermediate adsorption in structurally ordered substituted PdCu3 intermetallic nanoparticles for enhanced ethanol oxidation reaction

Boosting Hydrogen Production by Selective Anodic Electrooxidation of Ethanol over Trimetallic PdSbBi Nanoparticles: Composition Matters

The conventional hydrogen evolution from water electrolysis is severely impeded by the sluggish kinetics of oxygen evolution reaction (OER). In this work, an integrated electrolysis system of replacing the anodic OER with a thermodynamically favorable ethanol oxidation reaction (EOR) has been developed by using PdSbBi/C as an electrocatalyst. To maximize the EOR performance, the composition of PdSbBi nanoparticles is tuned by varying the ratio of Sb and Bi precursors. Ternary PdSbBi-based electrocatalysts exhibit enhanced activity and stability toward EOR compared to commercial Pd/C and binary catalysts. In particular, the Pd₇₆Sb₁₇Bi₇/C catalyst delivers a very high specific activity up to 52.4 mA cm^-2 and mass activity of 2.66 A mg^-1_Pd. Besides, this EOR process is demonstrated to have high selectivity with acetic acid as the oxidation product in the electrolyte. When coupled with a cathodic platinum mash, the two-electrode electrolyzer cell requires a voltage input of merely 0.61 V to afford a current density of 10 mA cm^-2. Density functional theory calculations reveal that the presence of Sb and Bi can promote the adsorption of hydroxide ions and facilitate the removal of reaction intermediates in the EOR pathway. This work provides a novel catalyst for the energy-efficient coproduction of acetic acid and hydrogen fuel.

Abundant (110) Facets on PdCu3 Alloy Promote Electrochemical Conversion of CO2 to CO

Electrochemical conversion of CO₂ to high-value chemical fuels offers a promising strategy for managing the global carbon balance but faces huge challenges due to the lack of effective electrocatalysts. Here, we reported PdCu₃ alloy nanoparticles with abundant exposed (110) facets supported on N-doped three-dimensional interconnected carbon frameworks (PdCu₃/NC) as an efficient and durable electrocatalyst for electrochemical CO₂ reduction to CO. The catalyst exhibits extremely high intrinsic CO₂ reduction selectivity for CO production with a Faraday efficiency of nearly 100% at a mild potential of -0.5 V. Moreover, a rechargeable high-performance Zn-CO₂ battery with PdCu₃/NC as a cathode is developed to deliver a record-high energy efficiency of 99.2% at 0.5 mA cm^-2 and rechargeable stability of up to 133 h. Theoretical calculations elucidate that the exposed (110) facet over PdCu₃/NC is the active center for CO₂ activation and rapid formation of the key *COOH intermediate.

Deciphering the Role of Substitution in Transition-Metal Phosphorous Trisulfide (100) Surface: A Highly Efficient and Durable Pt-free ORR Electrocatalyst

Rational design and development of earth-abundant, cost-effective, environmentally benign and highly robust oxygen reduction reaction (ORR) electrocatalyst can circumvent the obstacles associated with large scale commercialization of fuel cell. Here using first-principles based density functional theory (DFT), we have computationally screened the potential and feasibility of transition-metal phosphorous trisulfides TMPS3(100) surfaces as efficient ORR electrocatalyst in acidic fuel cell application. MnPS3(100) surface emerges to be the best among TMPS3 surfaces with optimal O2 activation resulting very low overpotential. The study reveals that ORR occurs on MnPS3 surface via 4e reduction associative pathway where kinetically rate determining step (RDS) is O* + H2O formation with an activation barrier of 0.66 eV. Substitution in half of the Mn sites of MnPS 3 (100) surface with Co enhances the ORR activity considerably. Mn0.5Co0.5PS3(100) surface exhibit an ultralow overpotential of 0.39 V vs RHE switching ORR pathway from associative to dissociative. Spontaneous dissociation of H2O2 on Mn0.5Co0.5PS3 proves 4e reduction pathway excluding 2e one. Electronic structure analysis reveals that pristine MnPS3(100) surface is a narrow band gap semiconductor which upon Co substitution transforms into a conducting metallic surface enhancing ORR activity.

Mxene coupled over nitrogen-doped graphene anchoring palladium nanocrystals as an advanced electrocatalyst for the ethanol electrooxidation

Development of good support materials is widely adopted as a valid strategy to fabricate high performance electrocatalysts for the ethanol oxidation reaction (EOR). In this study, the small diameter Ti₃C₂T_x MXene thin nanosheets inserted into three-dimensional nitrogen-doped grapheme (NG) was constructed via a facile hydrothermal method and employed as support materials for anchoring Pd nanocrystals (Pd/Ti₃C₂T_x@NG). The obtained-Pd/Ti₃C₂T_x@NG as EOR electrocatalyst in alkaline media outperforms the commercial Pd/C with better electrocatalytic activity, enhanced long-term stability and high CO tolerance. The Ti₃C₂T_x inserted into NG probably plays a key role for enhancing the properties of the synthesized-catalyst. Inserting Ti₃C₂T_x into NG allows the electrocatalysts to have high porosity, surface hydrophilicity, sufficient number of anchor sites for Pd nanocrystals and modifies its electronic properties, which can promote the electrocatalytic activity and durability. The enhanced EOR performance endows Pd/Ti₃C₂T_x@NG with great application potential in fuel cells as an anode catalyst. Furthermore, the prepared Ti₃C₂T_x@NG is also suitable in various desired applications, especially other oxidation reactions.