Morphology Effect of Ir/La₂O₂CO₃ Nanorods with Selectively Exposed {110} Facets in Catalytic Steam Reforming of Glycerol

Abstract

Tuning the morphology of nanocatalysts has been regarded as a powerful approach to high-performance heterogeneous catalysts, since the highly active facets might be selectively exposed to reactants. Herein, we report how the shape effect significantly improves the performance of Ir/La 2 O 2 CO 3 catalyst in the steam reforming of glycerol at high temperatures up to 650°C toward a sustainable hydrogen production. La 2 O 2 CO 3 nanorods (NRs) with different sizes and aspect ratios were synthesized for supporting Ir nanoparticles. Compared with conventional Ir/La 2 O 2 CO 3 , the NR catalysts considerably improved the activity, selectivity, and stability, allowing for a stable hydrogen production for 100 h without obvious deactivation. The role of the NRs was rationalized by XRD, XPS, TPR, TPD, and HRTEM analysis. The high performance of the NR catalyst is elucidated by the formation of hexagonal La 2 O 2 CO 3 NRs with selectively exposed {110} facets under reaction conditions, which strongly interact with Ir catalysts, thereby preventing the tiny catalyst particles from sintering at 650°C. A mechanistic insight is presented to understand the interaction based on the structure of the La 2 O 2 CO 3 supports.

Insight into the structure evolution and the associated catalytic behavior of highly dispersed Pt and PtSn catalysts supported on La2O2CO3 nanorods

“…24,25 As far as we know, La 2 O 2 CO 3 materials with specic morphology are scarcely studied in the hydrogenation process, although they are widely employed as important ingredients of heterogeneous catalysts in oxygen reduction reaction, steam reforming of glycerol and biofuel production because of their unique hydrotalcite-like structure and abundant active oxygen species. [26][27][28][29] In our previous work, preferential deposit of Pt on the {101} facets of La 2 O 2 CO 3 nanorods (denoted as Pt/LOC) is accounted for its superior reactive performance for CRAL hydrogenation to the Pt randomly dispersed on the particle-shaped counterpart. 30 Herein we carry out a systematic study on the physicochemical properties and the associated catalytic behavior of PtSn catalysts.…”

Ni/La2O3 Catalysts for Dry Reforming of Methane: Insights into the Factors Improving the Catalytic Performance

“…For all the three catalysts, an evident weight loss stage is observed between 400 and 700°C on the TGA curves, along with a strong exothermic peak around 650°C, which can be assigned to the combustion of the formed carbon deposits. In addition, a relatively smaller weight loss stage above 700°C is also observed, which can be attributed to the decomposition of La 2 O 2 CO 3 formed during the DRM reaction, [32] as also detected by XRD in Figure 6(D). As shown in Table 5, the coking amount of the spent catalysts followed the sequence of 5Ni/La 2 O 3 -TD > 5Ni/La 2 O 3 -PP > 5Ni/La 2 O 3 -GNC, which is in agreement with the activity and stability evaluation results.…”

“…Interestingly, on 5Ni/La 2 O 3 ‐GNC, both the exposed (110) facets of La 2 O 3 and (110) facets of La(OH) 3 are observed, indicating the surface of this catalyst is composed of two kinds of La compounds. As testified before, La 2 O 3 (110) planes can provided more medium‐strength alkaline sites, which can effectively enhance the adsorption and activation of CO 2 . As proved by Figure (C), the XRD results for the reduced catalysts, in the reduced 5Ni/La 2 O 3 ‐PP and 5Ni/La 2 O 3 ‐GNC, a large quantity of La(OH) 3 has been formed, while in the reduced 5Ni/La 2 O 3 ‐TD, La 2 O 3 is still the major crystalline phase.…”

Fabrication of High‐aspect Ratio (HAR) Palladium Nanorod‐modified Electrodes for Raman Spectroelectrochemical Studies of Thiolate Desorption from HAR Nanomaterials

“…Changes in chemistry and catalytic activity have been described in previous work on low‐ and high‐aspect ratio nanoparticles/nanorods of the same material , but detailed mechanistic reasons underlying these differences have not yet appeared. Au and Ag nanorods are susceptible to dissolution by cyanide and nitrate, respectively, whereas spherical particles remain robust .…”

“…The anisotropic growth mechanisms that produce the HAR nano‐sized objects yield materials with enhanced fractions of selected crystal faces at their surfaces. Catalytic and electrocatalytic activity and selectivity are often thereby enhanced relative to that achieved at low‐aspect ratio nanomaterials . Additionally, polarization of the highly anisotropic nanoscale structural features by incoming photons can generate exceptionally strong local electromagnetic fields at the surface of the nano‐object, yielding greatly field‐enhanced catalytic activity for selected reactions and strong surface‐enhanced Raman effects compared to those possible at isotropic nanoparticles .…”