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

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
PtCu subnanoclusters epitaxial on octahedral PtCu/Pt skin matrix as ultrahigh stable cathode electrocatalysts for room-temperature hydrogen fuel cells
Nano Research 2023, 16 (2): 2252-2258
Published: 03 November 2022

Achieving stable surface structures of metal catalysts is an extreme challenge for obtaining long-term durability and meeting industrial application requirements. We report a new class of metal catalyst, Pt-rich PtCu heteroatom subnanoclusters epitaxially grown on an octahedral PtCu alloy/Pt skin matrix (PtCu1.60), for the oxygen reduction reaction (ORR) in an acid electrolyte. The PtCu1.60/C exhibits an 8.9-fold enhanced mass activity (1.42 A·mgPt−1) over that of commercial Pt/C (0.16 A·mgPt−1). The PtCu1.60/C exhibits 140,000 cycles durability without activity decline and surface PtCu cluster stability owing to unique structure derived from the matrix and epitaxial growth pattern, which effectively prevents the agglomeration of clusters and loss of near-surface active sites. Structure characterization and theoretical calculations confirm that Pt-rich PtCu clusters favor ORR activity and thermodynamic stability. In room-temperature polymer electrolyte membrane fuel cells, the PtCu1.60/C shows enhanced performance and delivers a power density of 154.1/318.8 mW·cm2 and 100 h/50 h durability without current density decay in an air/O2 feedstock.

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

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

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.

Research Article Issue
Interface-rich Au-doped PdBi alloy nanochains as multifunctional oxygen reduction catalysts boost the power density and durability of a direct methanol fuel cell device
Nano Research 2022, 15 (7): 6036-6044
Published: 20 April 2022

The development of cathode oxygen reduction reaction (ORR) catalysts with high characteristics for practical, direct methanol fuel cells (DMFCs) has continuously increased the attention of researchers. In this work, interface-rich Au-doped PdBi (PdBiAu) branched one-dimensional (1D) alloyed nanochains assembled by sub-6.5 nm particles have been prepared, exhibiting an ORR mass activity (MA) of 6.40 A·mgPd−1 and long-term durability of 5,000 cycles in an alkaline medium. The MA of PdBiAu nanochains is 46 times and 80 times higher than that of commercial Pt/C (0.14 A·mgPt−1) and Pd/C (0.08 A·mgPd−1). The MA of binary PdBi nanochains also reaches 5.71 A·mgPd−1. Notably, the PdBiAu nanochains exhibit high in-situ carbon monoxide poisoning resistance and high methanol tolerance. In actual DMFC device tests, the PdBiAu nanochains enhance power density of 140.1 mW·cm−2 (in O2)/112.4 mW·cm−2 (in air) and durability compared with PdBi nanochains and Pt/C. The analysis of the structure–function relationship indicates that the enhanced performance of PdBiAu nanochains is attributed to integrated functions of surficial defect-rich 1D chain structure, improved charge transfer capability, downshift of the d-band center of Pd, as well as the synergistic effect derived from “Pd-Bi” and/or “Pd-Au” dual active sites.

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