Surface Structure Engineering of PtPd Nanoparticles for Boosting Ammonia Oxidation Electrocatalysis.
Zhenzhong LiuYi LiXiangsong ZhangShaosheng RaoJinghan LiWenlong WangZhongti SunJuan YangPublished in: ACS applied materials & interfaces (2022)
Achieving high catalytic ammonia oxidation reaction (AOR) performance of Pt-based catalysts is of paramount significance for the development of direct ammonia fuel cells (DAFCs). However, the high energy barrier of dehydrogenation of *NH 2 to *NH and easy deactivation by *N on the Pt surface make the AOR show sluggish kinetics. Here, we have put forward an alloying and surface modulation tactic to optimize Pt catalysts. Several spherical PtM (M = Co, Ni, Cu, and Pd) binary nanoparticles were controllably loaded on reduced graphene oxide (rGO). Among others, spherical PtPd nanoparticles displayed the most efficient catalytic activity. Further surface engineering of PtPd nanoparticles with a cubic-dominant structure has resulted in dramatic AOR activity improvements. The optimized (100) Pt 85 Pd 15 /rGO exhibited a low onset potential (0.467 V vs reversible hydrogen electrode (RHE)) and high peak mass activity (164.9 A g -1 ), much better than commercial Pt/C. Nevertheless, a short-term stability test along with morphology, structure, and composition characterizations indicate that the leaching of Pd atoms from PtPd alloy nanoparticles, their structure transformations, and the possible poisoning effects by the N-containing intermediates could result in the catalyst's activity loss during the AOR electrocatalysis. A temperature-dependent electrochemical test confirmed a reduced activation energy (∼12 kJ mol -1 decrease) of cubic-dominant PtPd compared to Pt/C. Density functional theory calculations further demonstrated that Pd atoms in Pt decrease the reaction energy barrier of electrochemical dehydrogenation of *NH 2 to *NH, resulting in an excellent catalytic activity for the AOR.
Keyphrases
- reduced graphene oxide
- room temperature
- density functional theory
- gold nanoparticles
- ionic liquid
- molecular dynamics
- metal organic framework
- highly efficient
- induced apoptosis
- hydrogen peroxide
- visible light
- drug delivery
- walled carbon nanotubes
- molecular dynamics simulations
- heavy metals
- high resolution
- aqueous solution
- nitric oxide
- cell death
- pi k akt
- carbon nanotubes
- municipal solid waste