Optimal coordination-site exposure engineering in porous platinum for outstanding oxygen reduction performance

Han, Cheng; Liu, Si; Hao, Zikai; Wang, Jingyu; Liu, Bojun; Liu, Guangyao; Wu, Xiaojun; Chu, Wangsheng; Wu, Changzheng; Xie, Yi

doi:10.1039/c9sc01078e

Cited by 23 publications

(34 citation statements)

References 38 publications

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“…Some important progress in recent years has been made in the development of porous Pt‐based ORR electrocatalysts, in which the intrinsic activity of the catalytic sites is optimized by tuning the local coordination environment around the Pt atoms. [ 70 ] For example, Cheng et al reported the synthesis of grain boundary‐rich, porous Pt electrocatalyst consisting of 3 nm nanocrystals by a confined space pyrolysis strategy ( Figure a). [ 70a ] Their DFT calculation demonstrated that the Pt sites at the grain boundaries had a higher coordination number than those on isolated Pt grains (Figure 9b), and this was supported by X‐ray absorption fine structure (XAFS) analysis.…”

Section: Porous Orr Electrocatalystsmentioning

confidence: 99%

“…[ 70 ] For example, Cheng et al reported the synthesis of grain boundary‐rich, porous Pt electrocatalyst consisting of 3 nm nanocrystals by a confined space pyrolysis strategy ( Figure a). [ 70a ] Their DFT calculation demonstrated that the Pt sites at the grain boundaries had a higher coordination number than those on isolated Pt grains (Figure 9b), and this was supported by X‐ray absorption fine structure (XAFS) analysis. This allowed the former to exhibit more optimal adsorption energies toward oxygenated species during ORR.…”

Section: Porous Orr Electrocatalystsmentioning

confidence: 99%

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Active Site Engineering in Porous Electrocatalysts

et al. 2020

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between electrical and chemical energy to store off-peak electricity produced from these resources. The opportunities relate to the fact that electrocatalytic reactions can be employed to convert these excess and off-peak electricity into chemical bonds in molecules. A fascinating prospect is the utilization of renewable electricity for the conversion of abundant resources such as H 2 O, N 2 , and CO 2 into synthetic fuels such as hydrogen, ammonia, hydrocarbons, and alcohols under ambient conditions (Figure 1). Through the reverse processes, clean electricity can be generated from the products, for example, via hydrogen-, ammonia-, or alcohol-powered fuel cells, ultimately resulting in a closed water cycle, nitrogen cycle, or carbon cycle. Hydrogen production via electrocatalytic water splitting, which may enable the hydrogen economy, is a notable example to these. [2] At present, the annual hydrogen production worldwide exceeds more than 65 million tons, mainly for industrial uses such as petroleum refining and ammonia synthesis. Unfortunately, most of the hydrogen is produced from fossil fuels through steam methane reforming and coal gasification and is accompanied by large emission of the greenhouse gas CO 2. Producing hydrogen from water using renewable electricity provides a green and sustainable pathway for future hydrogen energy cycle. In a similar vein, renewable energy-powered electrocatalysis of CO 2 and N 2 reduction produces high-value fuels or fine chemicals such as formic acid (HCOOH), carbon monoxide (CO), methanol (CH 3 OH), and ammonia (NH 3) under ambient conditions. [3] The use of these renewable fuels (e.g., hydrogen and alcohols), instead of petroleum-based fuels, for transportation applications is receiving unprecedented attention because the former are more environmentally friendly and sustainable. Fuel cell technologies based on these fuels can reliably supply electrical energy and are, thus, highly desired for running emerging electric vehicles. [4] To realize the water cycle, carbon cycle, and nitrogen cycle described above, the central reactions are the hydrogen evolution reaction (HER), the CO 2 reduction reaction (CO 2 RR), and the nitrogen reduction reaction (NRR), as well as the oxygenrelated reactions, including the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR), which are important half reactions in electrolyzers and fuel cells, respectively. In these energy conversion processes, electrocatalysts are indispensable. The desired electrocatalysts should both Electrocatalysis is at the center of many sustainable energy conversion technologies that are being developed to reduce the dependence on fossil fuels. The past decade has witnessed significant progresses in the exploitation of advanced electrocatalysts for diverse electrochemical reactions involved in electrolyzers and fuel cells, such as the hydrogen evolution reaction (HER), the oxygen reduction reaction (ORR), the CO 2 reduction reaction (CO 2 RR), the nitrogen reduction reaction (NRR), and the oxyge...

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Section: Porous Orr Electrocatalystsmentioning

confidence: 99%

Section: Porous Orr Electrocatalystsmentioning

confidence: 99%

Active Site Engineering in Porous Electrocatalysts

et al. 2020

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“…It has been demonstrated that the performance of catalysts strongly depends on the surface structures [15][16][17][18][19][20]. In particular, previous studies demonstrated that the catalytic structures rich in grain boundaries usually exhibit high catalytic activities, such as ORR, CO2 reduction reaction (CO2RR), and methanol oxidation reaction (MOR) [13,[21][22][23][24]. The grain boundaries can be developed inside polycrystalline crystals, but the density is usually scarce because of the consequent lattice distortion induced instability [25,26].…”

Section: Introductionmentioning

confidence: 99%

Enhancement of oxygen reduction reaction activity by grain boundaries in platinum nanostructures

Zhu

Wang

et al. 2020

Nano Res.

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Systematic control of grain boundary densities in various platinum (Pt) nanostructures was achieved by specific peptide-assisted assembly and coagulation of nanocrystals. A positive quadratic correlation was observed between the oxygen reduction reaction (ORR) specific activities of the Pt nanostructures and the grain boundary densities on their surfaces. Compared to commercial Pt/C, the grain-boundary-rich strain-free Pt ultrathin nanoplates demonstrated a 15.5 times higher specific activity and a 13.7 times higher mass activity. Simulation studies suggested that the specific activity of ORR was proportional to the resident number and the resident time of oxygen on the catalyst surface, both of which correlate positively with grain boundary density, leading to improved ORR activities.

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“…At present, Pt is still the efficient ORR and HER catalysts because of its high electrocatalytic performance. But the amounts of Pt need to reach 20 wt.% and even 20-40 wt.% for using as HER and ORR catalysts, respectively, which limits the practical application due to its limited reserve and high price [6,7]. Although Pt-free electrocatalysts, such as phosphides [8], chalcogenides [9], oxides [10,11], nitrides [12] and carbon based materials [13], have shown promising HER and/or ORR activities, it is rather difficult to completely replace Pt with these catalysts due to the significant gap in performance between the present state-of-the-art Pt-based catalysts and the Pt-free catalysts.…”

Section: Introductionmentioning

confidence: 99%

Size effects of platinum particles@CNT on HER and ORR performance

Tian

Meng

et al. 2020

Sci. China Mater.

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Platinum (Pt) is an efficient catalyst for hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR), but the debate of the relevance between the Pt particle size and its electrocatalytic activity still exist. The strong metal-support interaction (SMSI) between the metal and carrier causes the charge transfer and mass transport from the support to the metal. Herein, Pt species (0.5 wt.%) with various particle sizes supported on carbon nanotubes (CNTs) have been synthesized by a photo-reduction method. Thẽ 1.5 nm-sized Pt catalyst shows much higher HER performance than the counterparts in all pH solutions, and the mass activity of it is even 23-36 times that of Pt/C. While for ORR, the~3 nm-sized Pt catalyst exhibits the optimal performance, and the mass activity is 3 times and even 16 times that of Pt/C in acidic and alkaline media, respectively. The high HER and ORR performances of the~1.5 nm-and~3 nm-sized Pt catalysts benefit from the SMSI between Pt and the CNTs matrix and the higher ratio of face sites to edge sites, which is meaningful for the design of efficient electrocatalysts for renewable energy application.

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Optimal coordination-site exposure engineering in porous platinum for outstanding oxygen reduction performance

Abstract: Optimal coordination-site exposure engineering in porous platinum brings ultrahigh activity and durability for the fuel cell oxygen reduction reaction.

Cited by 23 publications

References 38 publications

Active Site Engineering in Porous Electrocatalysts

Active Site Engineering in Porous Electrocatalysts

Enhancement of oxygen reduction reaction activity by grain boundaries in platinum nanostructures

Size effects of platinum particles@CNT on HER and ORR performance

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