Tunable nano-distribution of Pt on TiO2 nanotubes by atomic compression control for high-efficient oxygen reduction reaction

Achieving cost-competitive catalysts with low Pt utilization and improving the durability caused by the corrosion of supports in the catalysts must be solved for the high activity in the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). Here, we show an innovative technique to synthesize unique nanotube supports for the ORR catalysts based on the combination of experimental and theoretical studies. The method precisely controls the atomic morphology of TiO2 nanotubes by a small amount of atomic substitution, maximizing their efficiency as catalyst supports. The spontaneous change in the size and dispersibility of the Pt nanoparticles appears by only small lattice contraction on the metal-doped TiO2 (M-TiO2) nanotubes. To study this phenomenon, various dopants such as V, Nb, and Cr were added to the M-TiO2 nanotubes. The compression arising out of each metal-support interaction resulted in the diverse shape of the nanoparticles on similar supports, which is revealed based on the X-ray absorption fine structure (XAFS) and the density-functional-theory (DFT) calculations. Based on a comprehensive understanding of inter-and intracrystal interactions in the small substitution doping process, we can control the size and dispersibility of the Pt nanoparticles, catalytic activity, and durability of catalysts for ORR.11Nsciescopu

Crystal Facet-Manipulated 2D Pt Nanodendrites to Achieve an Intimate Heterointerface for Hydrogen Evolution Reactions

© Despite the Pt-catalyzed alkaline hydrogen evolution reaction (HER) progressing via oxophilic metal-hydroxide surface hybridization, maximizing Pt reactivity alongside operational stability is still unsatisfactory due to the lack of well-designed and optimized interface structures. Producing atomically flat two-dimensional Pt nanodendrites (2D-PtNDs) through our 2D nanospace-confined synthesis strategy, this study tackles the insufficient interfacial contact effect during HER catalysis by realizing an area-maximized and firmly bound lateral heterointerface with NiFe-layered double hydroxide (LDH). The well-oriented {110} crystal surface exposure of Pt promotes electronic interplay that bestows strong LDH binding. The charge-relocated interfacial bond in 2D-PtND/LDH accelerates the hydrogen generation steps and achieves nearly the highest reported Pt mass activity enhancement (∼11.2 times greater than 20 wt % Pt/C) and significantly improved long-term operational stability. This work uncovers the importance of the shape and facet of Pt to create heterointerfaces that provide catalytic synergy for efficient hydrogen production.11Nsciescopu

Computational Discovery of Optimal Dopants for Nickel Iron Oxyhydroxide to Enhance OER Activity and Saline Water Compatibility

A strategic approach has been proposed for designing robust, high-performing oxygen evolution reaction (OER) catalysts tailored for saline water splitting. By employing a density functional theory (DFT)-based computational screening process, a set of promising dopants were identified from a range of 26 3d to 5d transition metals, with the aim of enhancing the activity and saline water resilience of the catalysts. The screening methodology was 3-fold, encompassing evaluations of OER energetics, chlorine evolution reaction (ClER) energetics, and chloride-corrosion energetics. The screening led to the selection of Sc as a promising dopant, which substantially elevated the performance of the NiFeOOH catalysts. This improvement was validated by an 87 mV decrease in OER overpotential at 100 mA/cm2 and a 100 h stability test under 1 M KOH + 0.5 M NaCl conditions. This study contributes to the understanding of the alkaline ClER and chloride-corrosion mechanisms, providing insights into catalyst behavior under saline conditions