Tai Thien Huynh

With increasing atmospheric CO ₂ concentrations and their associated environmental challenges, the electrochemical carbon fixation process is of interest as a green and sustainable strategy to obtain future carbon‐neutral energy cycles. Nonetheless, most existing catalysts still fail to meet the demands of the efficient CO ₂ conversion process because of limited activity, poor selectivity, and high cost. Two‐dimensional (2D) MXene‐based materials have currently gained growing attention as potential candidates for the electrocatalytic CO ₂ conversion process by their high conductivity, controllable surface chemistry, and intrinsic hydrophilicity. We herein critically summarize current progress in optimizing adsorption energies of key intermediates, product selectivity, and overall electrocatalytic efficiency of MXene‐based electrocatalysts through various modification strategies; namely, defect and doping engineering, surface and interfacial construction, alloying and single‐atom catalyst design, and synergistic coupling influences. The working mechanisms and structure–performance relationships of MXene‐derived catalysts for CO ₂ electrolysis and Li–CO ₂ batteries are elucidated. Finally, current challenges and prospects of MXene‐derived materials are discussed to provide valuable insights for designing advanced CO ₂ conversion electrocatalysts.

We herein construct the Ce-O-Ti interface bridge in the CeO_x/N-Ti₃C₂T_y heterojunction through an ultrasonic-assisted hydrothermal route as an efficient Pt-free hydrogen evolution electrocatalyst. The synergistic contribution of the heterogeneous Ce-O-Ti bridge and oxygen vacancies boosts the water dissociation and thus drastically reduces energy barriers of the hydrogen evolution reaction (HER). The optimal CeO_x/N-Ti₃C₂T_y material requires only a small overpotential (51.12 mV_RHE at 10 mA cm^-2) and has a low Tafel slope (51.87 mV dec^-1) and long-term stability with negligible changes in structural and morphological properties after at least 50 h of testing.

Designing electrocatalysts with the selective C─C bond breaking in ethanol electro‐oxidation is of interest as an efficient strategy to accelerate the large‐scale applications of direct ethanol fuel cells (DEFCs).Pt nanoparticles (NPs) are herein on N‐doped 2D Ti₃C₂T_x MXene via two‐step synthesis steps including NH₃‐assisted hydrothermal and NaBH₄‐assisted ethylene glycol reduction routes. With the selective C─C bond breaking, the as‐obtained 16 wt.% Pt/N‐Ti₃C₂T_x catalyst exhibits 435.35 mA mg_Pt⁻¹ mass activity and 0.83 mA cm⁻² specific activity, being 1.26‐ and 1.77‐fold increase compared to those of commercially available 20 wt.% Pt/C (346.21 mA mg_Pt⁻¹ and 0.47 mA cm⁻²). This originates from the advantages of unique 2D structures and the strong interplay between Pt NPs and nitrogen‐doped Ti₃C₂T_x. Also, the Pt/N‐Ti₃C₂T_x shows superior CO‐poisoning resistance and long‐term stability for the acidic ethanol electro‐oxidation reaction (EOR). This work demonstrates the potential of heteroatom‐doped Ti₃C₂T_x MXenes to increase the C₁ pathway selectivity and the catalytic performance of Pt‐based electrocatalysts in DEFCs.

Synergistic contributions of ternary alloys and TiO ₂ -based supports accelerate the formic acid electro-oxidation process via the dominant dehydrogenation pathway.

Ternary Pt-based structures are a positive progress in addressing the disadvantages of monometallic and bimetallic Pt-based alloys for the electrochemical oxidation process of simple alcohols, which is a vital half-reaction in fuel cell technologies. We herein report a facile NaBH₄-assisted ethylene glycol reduction process for fabricating a series of nanosized PtRuNi ternary alloys to explore the relationship between physicochemical properties and electrocatalytic behaviors for the acidic methanol oxidation reaction (MOR). Owing to a balance between lattice strain and synergistic effects, the Pt₆₀Ru₂₀Ni₂₀/C electrocatalyst shows the highest MOR efficiency with the mass activity/specific activity of 844.48 mA mg_Metal^-1/1.93 mA cm^-2, being a 1.94 and 2.38 times increase compared to those of the PtRu catalyst, respectively. Also, the Pt₆₀Ru₂₀Ni₂₀/C catalyst possesses superior CO-tolerance and durability in strongly acidic electrolytes. This work suggests that optimizing the surface strain and electronic effects can boost the overall MOR efficiency of multicomponent Pt-based materials, which can help to further develop next-generation catalysts for energy conversion-related technologies.

Although alloying Pt with Ru has recently been reported as an advanced catalyst for the hydrogen evolution reaction (HER), their electrocatalytic performance and high cost are major limitations of the electrochemical water‐splitting technology. Therefore, the study herein reports a doping strategy of Ni atoms into the RuPt lattice that not only further reduces the noble metal content but also enhances the overall HER efficiency via the formed synergistic effects. With boosting reaction kinetics, the as‐made ternary alloy catalyst exhibits improved HER efficiency, achieving a low overpotential/Tafel slope of 22.14 mV/23.92 mV dec⁻¹ in the 0.5 m H₂SO₄ and 46.52 mV/37.82 mV dec⁻¹ in the 1.0 m KOH electrolyte. Furthermore, the NiRuPt/Activated XC‐72 shows high TOFs (4.13 H₂ s⁻¹ at 50 mV/3.88 H₂ s⁻¹ at 100 mV in acidic/alkaline electrolyte) and great long‐term stability. This study suggests that the development of Pt‐based ternary nanoalloys is an attractive strategy for using low‐precious metal‐content catalysts for electrochemical energy‐related technologies.