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

Effective Screening Route for Highly Active and Selective Metal−Nitrogen‐Doped Carbon Catalysts in CO2 Electrochemical Reduction

To identify high-efficiency metal—nitrogen-doped (M—N—C) electrocatalysts for the electrochemical CO2-to-CO reduction reaction (CO2RR), a method that uses density functional theory calculation is presented to evaluate their selectivity, activity, and structural stability. Twenty-three M—N4—C catalysts are evaluated, and three of them (M = Fe, Co, or Ni) are identified as promising candidates. They are synthesized and tested as proof-of-concept catalysts for CO2-to-CO conversion. Different key descriptors, including the maximum reaction energy, differences of the *H and *CO binding energy (ΔG*H−ΔG*CO), and *CO desorption energy (ΔG*CO→CO(g)), are used to clarify the reaction mechanism. These computational descriptors effectively predict the experimental observations in the entire range of electrochemical potential. The findings provide a guideline for rational design of heterogeneous CO2RR electrocatalysts.11Nsciescopu