Ni-Catalyzed Growth of Graphene Layers during Thermal Annealing: Implications for the Synthesis of Carbon-Supported PtNi Fuel-Cell Catalysts

Facile synthesis of L10-PtFe/C intermetallic catalysts with superior catalytic durability for the oxygen reduction reaction

An o-PtFe/C intermetallic catalyst was prepared by a facile thermal reduction method with the average particle size of only 6.6 nm in the presence of urea. The loss of mass activity is only 25.9% after 50 000 cycles. This work provides guidance on the suppression of grain coarsening for high-temperature synthesis of Pt-based intermetallic catalysts.

Synthesis of Structurally Stable and Highly Active PtCo3 Ordered Nanoparticles through an Easily Operated Strategy for Enhanced Oxygen Reduction Reaction

Constructing robust and cost-effective Pt-based electrocatalysts with an easily operated strategy remains a crucial obstacle to fuel cell applications. Conventional Pt-based catalysts suffer from high Pt content and an arduous synthetic process. Herein, through the spray dehydration method and annealing treatment, facile producible synthesis of a small-sized (5.2 nm) low-Pt (10.5 wt %) ordered PtCo₃/C catalyst (O-PtCo₃/C) for oxygen reduction reaction is reported. The fast spray evaporation rate contributes to small size and uniform nucleation of nanoparticles (NPs) on carbon support. O-PtCo₃/C-600 exhibits efficient electrocatalytic performance with mass activity (MA) 6.0-fold and specific activity 3.9-fold higher than commercial Pt/C. The ordered chemical structure generates superior stability with merely 3.5% decay in MA after 10,000 potential cycles. Density functional theory calculations reveal that the enhanced catalytic performance originates from rational modification of d-band through strain and ordering effect and accompanying weaker adsorption of intermediate OH. This work highlights the potentials of low-Pt PtM₃-type ordered NPs for prospective fuel cell cathodic catalysis. The proposed facile and practical synthetic strategy also shows promising prospects for preparing effective Pt-based electrocatalysts.

Facile Synthesis of Quaternary Structurally Ordered L12-Pt(Fe, Co, Ni)3 Nanoparticles with Low Content of Platinum as Efficient Oxygen Reduction Reaction Electrocatalysts

Synthesis of electrocatalysts for oxygen reduction reaction (ORR) with not only prominent electrocatalytic performance but also a low amount of Pt is the urgent challenge in the popularization of fuel cells. In this work, through a facile synthetic strategy of spray dehydration on a solid surface and annealing process, we demonstrate the first manufacture of quaternary structurally ordered PtM₃ (M = transition metal) intermetallic nanoparticles (NPs), Pt(Fe, Co, Ni)₃, in order to lower the content of Pt. The atomic contents of Pt, Fe, Co, and Ni are equal and the chemical structure of Pt(Fe, Co, Ni)₃ is a cubic L1₂-ordered structure. L1₂-Pt(Fe, Co, Ni)₃/C electrocatalysts exhibit enhanced electrocatalytic performance toward ORR with mass activity (MA) 6.6 times higher than the commercial Pt/C and a minimal loss of 17% in MA and 1.5% loss in specific activity (SA) after 10 000 potential cycles at 0.9 V. Furthermore, the stability behavior is confirmed to be attributed to the coaction of particle sizes and the ordering effect. Compared with traditional Pt-based electrocatalysts in the stoichiometric forms of Pt₃M and PtM, L1₂-Pt(Fe, Co, Ni)₃ intermetallic NPs exhibit excellent performance and higher cost effectiveness. Moreover, this work also proposes a facile and effective synthetic strategy for manufacturing multicomponent Pt-based electrocatalysts for ORR.

Rational Development of Structurally Ordered Platinum Ternary Intermetallic Electrocatalysts for Oxygen Reduction Reaction

Structurally ordered intermetallic structure is an efficient catalyst design strategy to significantly improve the catalytic performance of Pt alloy electrocatalysts for oxygen reduction reaction in fuel cells. However, a high structural ordering degree generally relies on high-temperature annealing, which results in detrimental catalyst particle sintering. Herein, we reveal that the incompatibility between high ordering degree and minimum particle sintering during thermal annealing can be resolved through rational development of structurally ordered Pt ternary alloys. Ordering transformation mediated by high-temperature annealing of three representative Pt ternary alloys (Pt–Fe–Co, Pt–Ni–Co and Pt–Fe–Ni) at a similar Pt composition was systematically studied. It was found that Fe can significantly promote the structural ordering due to a faster atomic diffusion, whereas Co can effectively inhibit the particle sintering. As a result of the synergy between Co and Fe, the ordered PtCoFe catalyst exhibited the highest ordering degree after thermal annealing at 600 °C with the minimum nanoparticle growth, leading to the highest catalytic activity (0.65 A/mgPt at 0.9 V, 4 times that of pure Pt catalyst) and best stability (16% drop after 10,000 potential cycles). This study provides important clues for the rational design of high-performance structurally ordered ternary Pt alloys.

7.35% Efficiency rear-irradiated flexible dye-sensitized solar cells by sealing liquid electrolyte in a groove

Transparent Ni–Se alloys are successfully synthesized by an electrochemical deposition strategy and employed as counter electrode (CE) materials in rear-irradiated flexible dye-sensitized solar cells (DSSCs). The good catalytic activity, and cost-effectiveness highlight the potential applications of the transparent Ni–Se alloy CEs in flexible DSSCs.