Research Article Issue
Boosting alkaline hydrogen evolution performance by constructing ultrasmall Ru clusters/Na+, K+-decorated porous carbon composites
Nano Research 2023, 16 (7): 8836-8844
Published: 13 March 2023
Abstract PDF (28.5 MB) Collect

The construction of efficient and durable electrocatalysts with highly dispersed metal clusters and hydrophilic surface for alkaline hydrogen evolution reaction (HER) remains a great challenge. Herein, we prepared hydrophilic nanocomposites of Ru clusters (~ 1.30 nm) anchored on Na+, K+-decorated porous carbon (Ru/Na+, K+-PC) through hydrothermal method and subsequent annealing treatment at 500 °C. The Ru/Na+, K+-PC exhibits ultralow overpotential of 7 mV at 10 mA·cm−2, mass activity of 15.7 A·mgRu−1 at 100 mV, and long-term durability of 20,000 cycles potential cycling and 200 h chronopotentiometric measurement with a negligible decrease in activity, much superior to benchmarked commercial Pt/C. Density functional theory based calculations show that the energy barrier of H–OH bond breaking is efficiently reduced due to the presence of Na and K ions, thus favoring the Volmer step. Furthermore, the Ru/Na+, K+-PC effectively employs solar energy for obtaining H2 in both alkaline water and seawater electrolyzer. This finding provides a new strategy to construct high-performance and cost-effective alkaline HER electrocatalyst.

Research Article Issue
Low-coordinated surface sites make truncated Pd tetrahedrons as robust ORR electrocatalysts outperforming Pt for DMFC devices
Nano Research 2022, 15 (9): 7951-7958
Published: 23 June 2022
Abstract PDF (3.4 MB) Collect

Developing highly stable and active non-Pt oxygen reduction reaction (ORR) electrocatalysts for power generation device raises great concerns and remains a challenge. Here, we report novel truncated Pd tetrahedrons (T-Pd-Ths) enclosed by {111} facets with excellent uniformity, which have both low-coordinated surface sites and distinct lattice distortions that would induce “local strain”. In alkaline electrolyte, the T-Pd-Ths/C achieves remarkable ORR specific/mass activity (SA/MA) of 2.46 mA·cm−2/1.69 A·mgPd−1, which is 12.3/16.9 and 10.7/14.1 times higher than commercial Pd/C and Pt/C, respectively. The T-Pd-Ths/C also exhibits high in-situ carbon monoxide (CO) tolerance and 50,000 cycles durability with an activity loss of 7.69% and morphological stability. The rotating ring-disk electrode (RRDE) measurements show that a 4-electron process occurs on T-Pd-Ths/C. Theoretical calculations demonstrate that the low-coordinated surface sites contribute largely to the enhancement of ORR activity. In actual direct methanol fuel cell (DMFC) device, the T-Pd-Ths/C delivers superior open-circuit voltage (OCV) and peak power density (PPD) to commercial Pt/C from 25 to 80 °C, and the maximum PPD can reach up to 163.7 mW·cm−2. This study demonstrates that the T-Pd-Ths/C holds promise as alternatives to Pt for ORR in DMFC device.

Research Article Issue
PtCu3 nanoalloy@porous PWOx composites with oxygen container function as efficient ORR electrocatalysts advance the power density of room-temperature hydrogen-air fuel cells
Nano Research 2022, 15 (10): 9010-9018
Published: 21 June 2022
Abstract PDF (20.1 MB) Collect

It is challenging and desirable to construct Pt-based nanocomposites with oxygen storage function as efficient oxygen reduction reaction (ORR) catalysts for practical proton exchange membrane fuel cells (PEMFCs). Herein, we achieve novel porous nanocomposites of PtCu3 nanoalloys-embedded in the PWOx matrix (PtCu3@PWOx), which has an oxygen container feature. The PtCu3@PWOx/C exhibits an ultrahigh mass activity (MA) of 3.94 A·mgPt−1 for ORR, which is 26.3 times as high as the commercial Pt/C and the highest value ever reported for PtCu-based binary system. Theoretical calculations reveal that the compressive strain and d-band center downshift of Pt intrinsically contribute to the excellent ORR performance. In H2-air PEMFCs at room temperature, furthermore, the PtCu3@PWOx/C delivers a high power density (218.6 mW·cm−2), much superior to commercial Pt/C (131.6 mW·cm−2). In H2-O2 PEMFCs, PtCu3@PWOx/C outputs a maximum power density of 420.1 mW·cm−2. This work provides an effective idea for designing oxygen-storing ORR catalysts used for practical room-temperature H2-air fuel cells.

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