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To improve the stability of molybdenum carbide catalysts in dimethyl ether steam reforming (DSR), the inactivation mechanism and the performance of Pt modified catalyst has been investigated. The Mo2C oxidation induced by H2O is verified to be the main reason of catalytic deactivation. After modified with Pt, the H2 production rate and selectivity are greatly enhanced, reaches 1605 μmol min−1·gcat−1 at 350 °C, in comparison to that of the Mo2C/Al2O3 catalyst. Moreover, the 2%Pt–Mo2C/Al2O3 catalyst is more stable with only 20% activity loss after 50 h on stream compares to the 73% activity loss in 12 h with Mo2C/Al2O3 catalyst. By means of in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), the enhancement brought by Pt is ascribed to the consumption acceleration of intermediate oxygen species on catalyst surface and the decline of onset temperature of DSR reaction. It is expected that these findings can lead us to more practical molybdenum carbide catalysts in DSR.

In this work, well-ordered platinum (Pt) nanocubes (NCs), with precise control on the size and the spatial arrangement, are synthesized from a microemulsion overgrowth in a block copolymer (BC) nanotemplate. The nanovials on this self-assembled BC template serve as microreactors for the reduction of the HCl/H

Designing Pt-based nanoparticle (NP) catalysts is of great interest for the lowering of Pt usage and the enhancement of catalytic activity on the proton-exchange membrane fuel cells (PEMFCs). However, it is still challenging to develop well-arrayed catalyst NPs on supports over multiple-length scales. Herein, we presented a facile strategy of producing well-ordered Pt-based NPs toward oxygen reduction reaction (ORR) catalysts assisted by the self-assembly of block copolymers. In contrast to the conventional Pt/C ORR catalysts with a random dispersion on carbon, the as-prepared Pt, PtCo, and PtCo@Pt NPs in our work were hexagonally arranged with a uniform quasi-spherical shape and ordered distribution. The systematic study related to their ORR activities revealed that the PtCo@Pt core-shell NP arrays were more active and more durable than PtCo, Pt, and the commercial Pt/C catalyst. In the rotating-disk electrode test, a half-wave potential (E1/2) of 0.86 V versus RHE and a 4-e ORR mechanism were found for PtCo@Pt. Single-cell performance showed that the current density and the peak power density of PtCo@Pt achieved 0.86 A/cm2@0.7 V and 1.05 W/cm2, respectively, with a Pt loading of ∼0.15 mg/cm2 on the cathode. Also, they held 81.4 and 82.9% retention, respectively, after the durability test in the single-cell test. Density functional theory calculation results revealed that PtCo@Pt NPs had a lower d-band center and a weaker oxygen binding energy compared to Pt and PtCo, which contributed to the enhancement of the ORR activity.

Self-assembly of di-blcok copolymers (di-BCs) with precise control on morphologies and structures of nanomaterials makes it a promising technology for catalyst preparation. However, applications of the BC-synthesized Pt nanoparticles (NPs) on fuel cell have less been discussed. The major challenge may be the difficulty in achieving high-density nanopatterns which require a low degree of polymerization but a high effective segment-segment interaction parameter of the BC templates. As a resolution, sequentially double- or triple-layered BC route provides a new density-increased idea of harnessing these materials. In present work, monolayer of ordered and high-dispersed Pt-NP arrays with a density 27-folded has been achieved by the multiple di-BC routes consisted of identical self-assembly and plasma-cleaning processes. The multiplication has been proved to be equivalent to the duplication and oriented translation of the initial Pt-NP arrays, which provides not only a well-defined approach to control the spacing precisely, but also a bottom-up process to synthesize hexagonal-arranged arrays with predicable densities. Electrochemistry shows that the density multiplication has no negative effects on the Pt utilization of the monolayer arrays, and a remarkable ECSA value of ∼114.5 m2 g−1 is found. Further characterization of the monolayer arrays as cathodic catalysts for PEMFC reveals that, neither the ohmic losses nor the mass-transport losses are enhanced after the density multiplication, and the power density of the PEMFC assembled here is significantly higher than that using commercial Pt/C catalysts. All the results demonstrate that the multiple di-BC approach has great potential in preparation of BC-synthesized Pt-NP arrays for fuel cell applications.

To fabricate effective and stable OER electrode in water electrolysis, self-doped TiO2 nanotube arrays which has a higher electrical conductivity than pristine TiO2 nanotube arrays was used as the support for loading IrO2. The self-doped TNTA was fabricated by a simple electrochemical reduction of TNTA in neutral electrolyte solution, and then IrO2 nano particles were deposited by pulse electro-deposition method. The cyclic voltammetric behavior, electrical conductivity and micro structure of self-doped TNTA prepared at different reduction potential were characterized to obtain an optimal performance, and self-doped TNTA prepared under −1.9 V (vs. Ag/AgCl) shows the best electrochemical performance. After depositing IrO2, the OER activity and stability of new electrodes were also determined. Due to the enhanced electrical conductivity of support, the mass activity of IrO2/self-doped TNTA are 50 times higher than IrO2/TNTA. The OER stability of new electrode was evaluated under constant current of 5 mA/cm2, IrO2/TNTA and IrO2/Ti were also tested for comparison. A higher stability of IrO2/self-doped TNTA electrode is observed than the other two electrodes, and XPS studies indicate a lower oxidation state of Ir in IrO2/self-doped TNTA, this shows a possible interactions between IrO2 and the new support.