Oxidatively induced exposure of active surface area during microwave assisted formation of Pt₃Co nanoparticles for oxygen reduction reaction

Abstract

The oxygen reduction reaction (ORR) is efficiently facilitated platinum catalysts alloyed with Co and reveal high electrochemically active surface area via rapid microwave synthesis.

Microwave-Induced Structural Ordering of Resilient Nanostructured L10-FePt Catalysts for Oxygen Reduction Reaction

“…For this process, we selected the 1:1 composition because this is the only mixture capable of forming a fully ordered L1 0 phase, specially aided by a reductive atmosphere (H 2 ). 20,26−29 The FePt(1:1) samples possessed a near 1:1 composition and without residual traces from the NH 4 NO 3 oxidant (see X-ray photoelectron spectra in Supporting Information Figure S3), similarly observed for Pt 3 Co. 18 Previously reported solid-state synthesis methods have shown that the metal ratio in the bulk samples corresponds well with the initial precursor composition. 15,18,19 Figure 2a shows the XRD patterns of the catalysts and display typical Pt/Pt-alloy reflections [i.e., Pt(111), Pt(200), and Pt(220)], 30,31 but notably, Fe-oxide features [between Pt(111) and Pt(200), see Supporting Information Figure S4] emerge only for samples with the highest Fe content, indicating that the majority of Fe is well intermixed into the Pt fcc lattice.…”

“…20,26−29 The FePt(1:1) samples possessed a near 1:1 composition and without residual traces from the NH 4 NO 3 oxidant (see X-ray photoelectron spectra in Supporting Information Figure S3), similarly observed for Pt 3 Co. 18 Previously reported solid-state synthesis methods have shown that the metal ratio in the bulk samples corresponds well with the initial precursor composition. 15,18,19 Figure 2a shows the XRD patterns of the catalysts and display typical Pt/Pt-alloy reflections [i.e., Pt(111), Pt(200), and Pt(220)], 30,31 but notably, Fe-oxide features [between Pt(111) and Pt(200), see Supporting Information Figure S4] emerge only for samples with the highest Fe content, indicating that the majority of Fe is well intermixed into the Pt fcc lattice. Interestingly, reflections corresponding to the superlattice fct structure [broad (110) peak] become more pronounced for samples with X = 1,2,3 (FePt(X:1)/C*), implying that MW treatment forms NPs under high temperatures.…”

“…An additional 1 h MW annealing treatment [step (ii) in Figure ] in a reductive atmosphere was performed for the FePt(1:1)/C* sample in order to investigate a further transformation into the structurally ordered L1 0 phase [denoted FePt(1:1)/C, without asterisk]. For this process, we selected the 1:1 composition because this is the only mixture capable of forming a fully ordered L1 0 phase, specially aided by a reductive atmosphere (H 2 ). ,− The FePt(1:1) samples possessed a near 1:1 composition and without residual traces from the NH 4 NO 3 oxidant (see X-ray photoelectron spectra in Supporting Information Figure S3), similarly observed for Pt 3 Co . Previously reported solid-state synthesis methods have shown that the metal ratio in the bulk samples corresponds well with the initial precursor composition. ,, …”

“…As such, a significant production cost reduction can be achieved while also being regarded as a green synthesis method. − So far, reported MW-based methods for FePt preparation are however restricted to complex multistep solvothermal routes, , thus offering limited advantages over conventional heating, and include a substantial usage of chemicals. Here, we exploit the advantageous MW-process, , to synthesize stable FePt NPs, firmly anchored to the carbon support, by a direct ∼5 min solid-state MW synthesis process. By this process, we establish structurally ordered L1 0 fct FePt NPs with a mass activity that represents a significant leap toward the theoretical maximum for fully ordered FePt NPs.…”

Solid-state synthesis of few-layer cobalt-doped MoS2 with CoMoS phase on nitrogen-doped graphene driven by microwave irradiation for hydrogen electrocatalysis

“…In addition, carbon nanomaterials act as excellent material support by facilitating the production of nanoparticulate structures, minimizing agglomeration, improving stability, and enhancing electron transport. [20][21][22][23] We, therefore, exploit the ability of nanocarbons to easily absorb microwaves to develop a solid-state synthesis process driven by microwave irradiation to produce cobalt-doped edgeterminated layered MoS 2 directly on nitrogen-doped reduce graphene oxide (N-rGO x ). The as-produced Co-MoS 2 exhibited the CoMoS phase, and only a slight segregation to cobalt suldes was observed at Co content above 15 at%.…”