Design of a new reactor-like high temperature near ambient pressure scanning tunneling microscope for catalysis studies

Abstract

Articles you may be interested inThe ReactorSTM: Atomically resolved scanning tunneling microscopy under high-pressure, high-temperature catalytic reaction conditions Rev. Sci. Instrum. 85, 083703 (2014) Here, we present the design of a new reactor-like high-temperature near ambient pressure scanning tunneling microscope (HT-NAP-STM) for catalysis studies. This HT-NAP-STM was designed for exploration of structures of catalyst surfaces at atomic scale during catalysis or under reaction conditions. In this HT-NAP-STM, the minimized reactor with a volume of reactant gases of ∼10 ml is thermally isolated from the STM room through a shielding dome installed between the reactor and STM room. An aperture on the dome was made to allow tip to approach to or retract from a catalyst surface in the reactor. This dome minimizes thermal diffusion from hot gas of the reactor to the STM room and thus remains STM head at a constant temperature near to room temperature, allowing observation of surface structures at atomic scale under reaction conditions or during catalysis with minimized thermal drift. The integrated quadrupole mass spectrometer can simultaneously measure products during visualization of surface structure of a catalyst. This synergy allows building an intrinsic correlation between surface structure and its catalytic performance. This correlation offers important insights for understanding of catalysis. Tests were done on graphite in ambient environment, Pt(111) in CO, graphene on Ru(0001) in UHV at high temperature and gaseous environment at high temperature. Atom-resolved surface structure of graphene on Ru(0001) at 500 K in a gaseous environment of 25 Torr was identified.

Development of a reaction cell for in-situ/operando studies of surface of a catalyst under a reaction condition and during catalysis

“…[12][13][14][15][16] Typically, the flow rate is in the range of 0.01-0.1 ml/min. Parallel to the method of filling gas to a UHV chamber, another method of creating a local high pressure environment in UHV was used in instrumentation of in-situ studies of catalysts; [17][18][19][20][21][22] in this method, a reaction cell can be integrated at the crossing point of directions of X-ray beam and trajectory of elections in energy analyzer (Figure 1(b)).…”

In situ Visualization of Cluster-mediated Oxidation Dynamics and Kinetics on Cu(111)

“…STM and preparation chambers feature base pressures of 4×10 -11 mbar and 6×10 -11 mbar, respectively [22][23] . The second system is equipped with High Pressure and High Temperature STM (HT-HP-STM, SPECS) 16,[24][25][26] , ambient pressure XPS (APXPS, SPECS), and cleaning facilities. LT-STM experiments were conducted in constant current mode at 78 K, using an electrochemically etched W tip.…”