Regulating Competitive Adsorption on Pt Nanoparticles by Introducing Pb to Expedite Hydrogen Production via Ammonia Oxidation

Abstract

Ammonia with a high hydrogen content is an ideal hydrogen carrier due to its mature storage and transport system. Ammonia electrooxidation is one of the most promising technologies for green and economic H2 production. However, ammonia oxidation reaction (AOR) is limited to a narrow potential window due to the slow kinetics and the competitive adsorption between the reactant and Had/OHad on active sites. Herein, an ultra-small PtPb alloy nanocatalyst is synthesized for AOR by the facile one-step solvothermal method. Experimental results demonstrate that the electronic structure of Pt is regulated by the introduction of Pb, inhibiting the competitive adsorption on Pt sites. Therefore, it exhibits improved AOR activity with a peak current density of 191.2 mA mg–1 Pt at 10 mV s–1, which is 1.97 times that of Pt/C. The good performance is attributed to the high hydrogen evolution overpotential property of Pb and the strong p–d electron interaction of PtPb, which effectively modulates the adsorption/desorption of intermediates at the Pt site. Hence, this work proposes a simple and effective strategy for designing efficient AOR catalysts, promoting the development of H2 production by AOR.

Interface Engineering of PtZn Alloy and Nb2O5 for Promoting Ammonia Oxidation Reaction and Hydrogen Evolution Reaction

“…To compare the AOR activity of the samples, CV tests are conducted (Figure a). The oxidation peak in the potential range of 0.5–0.9 V RHE represents the occurrence of AOR. , The AOR peak current density of PtZn-Nb 2 O 5 /C–II is 304.1 mA mg –1 Pt , which is about 1.54 and 2.31 times those of PtZn/C (198.0 mA mg –1 Pt ) and Pt/C (131.6 mA mg –1 Pt ), respectively. Besides, the AOR activity shows a volcano trend with the increase of Nb 2 O 5 content, specifically, the peak current density of PtZn-Nb 2 O 5 /C–II is higher than those of PtZn/C (198.0 mA mg –1 Pt ), PtZn-Nb 2 O 5 /C–I (240.8 mA mg –1 Pt ), and PtZn-Nb 2 O 5 /C–III (259.9 mA mg –1 Pt ).…”

“…The oxidation peak in the potential range of 0.5−0.9 V RHE represents the occurrence of AOR. 15,22 The AOR peak current density of PtZn-Nb shows a decrease in activity, which could be due to the insufficient conductivity of metal oxide. 48 In addition, the ECSA of different catalysts is measured in an Ar-saturated 0.1 M HClO 4 solution with a scan rate of 50 mV s −1 (Figure S8a).…”

“…11 Due to the adjustment of the electronic structure, Pt-based alloys possess moderate adsorption energy for intermediates, thus enhancing catalytic activity. Pt-based binary catalysts such as PtIr, 12 PtRu, 13 PtZn, 14 and PtPb 15 have been used for AOR. For instance, Jiang prepared PtIrZn alloy by electrodeposition, 16 which has better AOR activity in comparison with PtIr because the introduction of Zn hinders the competitive adsorption of hydrogen.…”

Awakening (220) as One More Active Facet of PtMo Alloy via Single‐Atom Doping to Boost Ammonia Electrooxidation in Direct Ammonia Fuel Cell

“…Furthermore, the chronoamperograms (CA) tests were performed at 0.65 V versus RHE in the electrolyte containing 1 m KOH and 0.1 m NH 3 for 3 h (Figure 3g). After the sharp current decay at the beginning for all electrocatalysts owing to the removal of non‐faradic double‐layer currents and deactivation by N ads poisoning, [ 36,37 ] the reaction reaches a steady state. The highest current density is generated by the optimal Ni 7 ‐Pt 86 Mo 7 catalyst (47.91 A g −1 ), which is superior to Pt 93 Mo 7 (26.04 A g −1 ), Ni 22 ‐Pt 71 Mo 7 (5.07 A g −1 ), and PtIr/C 40% (1.70 A g −1 ) at the end of the tests.…”

Minireview on the Electrocatalytic Ammonia Oxidation Reaction for Hydrogen Production and Sewage Treatment

“…Alloy catalysts can reduce the need for expensive and rare metals, such as Pt. These alloys include PtCu, PtIrZn, and PtPb . Moreover, considerable research endeavors have been devoted to alloying Pt with various metals. , This pursuit aims to enhance the catalytic activity while concurrently mitigating the deleterious effects of surface poisoning on the Pt catalyst .…”