No abstract

Tuning the intrinsic strain of Pt‐based nanomaterials has shown great promise for improving the oxygen reduction reaction (ORR) performance. Herein, reported is a tunable surface strain in penta‐twinned ternary Pt–Cu–Mn nanoframes (NFs). Pt–Cu–Mn ultrafine NFs (UNFs) exhibit ≈1.5% compressive strain compared to Pt–Cu–Mn pentagonal NFs (PNFs) and show the superior activity toward ORR in an alkaline environment. Specifically, the specific and mass activity of Pt–Cu–Mn UNFs are 3.38 mA cm−2 and 1.45 A mg−1, respectively, which is 1.45 and 1.71 times higher than that of Pt–Cu–Mn PNFs, demonstrating that compressive strain in NFs structure can effectively enhance the catalytic activity of ORR. Impressively, Pt–Cu–Mn UNFs exhibit 8.67 and 9.67 times enhanced specific and mass activity compared with commercial Pt/C. Theoretical calculations reveal that compression on the surface of Pt–Cu–Mn UNFs can weaken the bonding strengths and adsorption of oxygen‐containing intermediates, resulting in an optimal condition for ORR.

ZSM-5/SBA-16 (ZS) composite materials with different morphologies were synthesized successfully. The series supports were utilized to prepare NiMo/ZS for dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) hydrodesulfurization (HDS) reactions. Series ZS supports and NiMo/ZS were well characterized to investigate their structure–property relationship. The NiMo/ZS catalyst (NiMo/ZS-3) with uniform morphology and well-ordered pore channels showed the maximum k HDS and TOF values of DBT and 4,6-DMDBT HDS. The k HDS value (13.9 × 10–4 mol g–1 h–1) of DBT over NiMo/ZS-3 was more than 2 times greater than that over the reference NiMo/ZS-M catalyst (5.5 × 10–4 mol g–1 h–1), 3 times greater than that over the NiMo/SBA-16 catalyst (4.4 × 10–4 mol g–1 h–1), and almost 4 times greater than that over the NiMo/ZSM-5 catalyst (3.5 × 10–4 mol g–1 h–1). Furthermore, the k HDS value (8.4 × 10–4 mol g–1 h–1) of 4,6-DMDBT over NiMo/ZS-3 was more than 3 times greater than that over the reference NiMo/ZS-M catalyst (2.8 × 10–4 mol g–1 h–1), more than 4 times greater than that over the NiMo/SBA-16 catalyst (1.7 × 10–4 mol g–1 h–1), and almost 5 times greater than that over the NiMo/ZSM-5 catalyst (1.6 × 10–4 mol g–1 h–1). The superior DBT and 4,6-DMDBT HDS performances were assigned to the uniform morphology, well-ordered pore channels, and high B/L ratio of the NiMo/ZS-3 catalyst and the suitable dispersion of the MoS2 active phases. HYD was the preferential route for DBT HDS, while ISO was the preferential route for 4,6-DMDBT HDS because of the high B/L ratio of NiMo/ZS-3. Moreover, the DBT and 4,6-DMDBT HDS reaction networks of the series NiMo/ZS are presented.

Micro-mesoporous Beta-SBA-15 materials with platelet, sphere, short-rod and long-rod morphologies were in situ synthesized and used as the catalyst supports for hydro-upgrading of FCC gasoline.

Metal nanocrystals (NCs) are grown directly on the surface of reduced graphene oxide (rGO), which can maximize the rGO-NCs contact/interaction to achieve the enhanced catalytic activity. However, it is difficult to control the size and morphology of metal NCs by in situ method due to the effects of functional groups on the surface of GO, and as a result, the metal NCs/rGO hybrids are conventionally synthesized by two-step method. Herein, one-pot synthesis of Pt-Co alloy NCs is demonstrated with concave-polyhedrons and concave-nanocubes bounded by {hkl} and {hk0} high-index facets (HIFs) distributed on rGO. GO can affect the geometry and electronic structure of Pt-Co NCs. Thanks to the synergy of the HIFs and the electronic effect of the intimate contact/interaction between Pt-Co alloy and rGO, these as-prepared Pt-Co NCs/rGO hybrids presents enhanced catalytic properties for the electrooxidation of formic acid, as well as for the oxygen reduction reaction.