Bimetallic CuPd nanoparticles supported on ZnO or graphene for CO and CO conversion to methane and methanol.

Carbon dioxide (CO) and carbon monoxide (CO) hydrogenation to methane (CH) or methanol (MeOH) is a promising pathway to reduce CO emissions and to mitigate dependence on rapidly depleting fossil fuels. Along these lines, a series of catalysts comprising copper (Cu) or palladium (Pd) nanoparticles (NPs) supported on zinc oxide (ZnO) as well as bimetallic CuPd NPs supported on ZnO or graphene were synthesized various methodologies. The prepared catalysts underwent comprehensive characterization high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX) mapping, electron energy loss spectroscopy (EELS), X-ray diffraction (XRD), hydrogen temperature-programmed reduction and desorption (H-TPR and H-TPD), and deuterium temperature-programmed desorption (DO-TPD).

Electro-tuned catalysts: voltage-controlled activity selection of bimetallic exsolution particles.

In this work, we show how the activity states of bimetallic Ni-Fe catalysts exsolved from NdCaFeNiO (NCFNi) can be influenced electrochemically. The NCFNi parent oxide was employed in the form of thin film mixed conducting model electrodes, which were operated in a humid hydrogen atmosphere. By precisely controlling the oxygen chemical potential in the parent oxide electrode applying an electrochemical polarisation, we managed to selectively exsolve Ni nanoparticles from the perovskite lattice and study their catalytic activity switching characteristics.

Discrimination of coherent and incoherent cathodoluminescence using temporal photon correlations.

We present a method to separate coherent and incoherent contributions of cathodoluminescence (CL) by using a time-resolved coincidence detection scheme. For a proof-of-concept experiment, we generate CL by irradiating an optical multimode fiber with relativistic electrons in a transmission electron microscope. A temporal analysis of the CL reveals a large peak in coincidence counts for small time delays, also known as photon bunching.

Experimental realization of a π/2 vortex mode converter for electrons using a spherical aberration corrector.

In light optics, beams with orbital angular momentum (OAM) can be produced by employing a properly-tuned two-cylinder-lens arrangement, also called π/2 mode converter. It is not possible to convey this concept directly to the beam in an electron microscope due to the non-existence of cylinder lenses in commercial transmission electron microscopes (TEMs). A viable work-around are readily-available electron optical elements in the form of quadrupole lenses.