摘要：Controllable self-assembly of noble metal nanocrystals is of broad interest for the development of highly active electrocatalysts. Here we report an efficient arginine-mediated hydrothermal approach for the high-yield synthesis of cube-like Pt nanoassemblies （Pt-CNAs） with porous cavities and rough surfaces based on the self-assembly of zero dimensional Pt nanocrystals. In this process, arginine acts as the reductant, structure directing agent, and linker between adjacent nanocrystals. Interestingly, the Pt-CNAs exhibit single-crystal structures with dominant {100} facets, as evidenced by X-ray diffraction. Based on electrocatalytic studies, the as-synthesized Pt-CNAs exhibit improved electrocatalytic activity as well as good stability and CO tolerance in the methanol oxidation reaction. The Pt-CNA＇s good performance is attributed to their unique morphology and surface structure. We believe that the synthetic strategy outlined here could be extended to other rationally designed monometallic or bimetallic nanoassemblies for use in high performance fuel cells.

摘要：The design and synthesis of high‐performance and low‐cost electrocatalysts for the hydrogen evolution reaction(HER),a key half‐reaction in water electrolysis,are *** to their modest hydrogen adsorption energy,ruthenium(Ru)‐based nanomaterials are considered outstanding candidates to replace the expensive platinum(Pt)‐based HER *** this study,we developed an adsorption‐pyrolysis method to construct nitrogen(N)‐doped graphene aerogel(N‐GA)‐supported ultrafine Ru nanocrystal(Ru‐NC)nanocomposites(Ru‐NCs/N‐GA).The particle size of the Ru‐NCs and the conductivity of the N‐GA substrate can be controlled by varying the pyrolysis *** experiments reveal revealed that 10 wt%Ru‐NCs/N‐GA nanocomposites require overpotentials of only 52 and 36 mV to achieve a current density of 10 mA cm^(−2) in 1 mol/L HClO4 and 1 mol/L KOH electrolytes for HER,respectively,which is comparable to 20 wt%Pt/C *** from the ultrafine size and uniform dispersion of the Ru‐NCs,the synergy between Ru and the highly conductive substrate,and the anchoring effect of the N atom,the Ru‐NCs/N‐GA nanocomposites exhibit excellent activity and durability in the pH‐universal HER,thereby opening a new avenue for the production of commercial HER electrocatalysts.

摘要：The poor oxygen evolution reaction(OER)activity of two-dimensional(2 D)transition metal carbides(MXenes)is a major obstacle to their application in highperformance water splitting and fuel cells due to the high energy barriers for the absorption of ***,we demonstrate that the lattice oxygen of M_(n)X_(n-1)O_(2)MXenes can be activated by 0 D graphene quantum dots(GQDs),thereby activating the OER via the lattice-oxygen oxidation mechanism(LOM)instead of the conventional adsorbate evolving *** pH-dependent OER activity of M_(n)X_(n-1)O_(2)@GQDs and ^(18)O isotope-labelling experiments with time-of-flight secondary-ion mass spectrometry(TOF-SIMS)provide the direct evidence of ***,the activated lattice oxygen amount can be controlled by the *** as-prepared 0 D/2 D Ti_(3)C_(2)O_(2)@GQDs heterostructure delivers a highly reduced overpotential of 390 mV(bare Ti_(3)C_(2)O_(2):530 mV)at a benchmark current density of 10 mA cm^(-2).Through optimizing the thickness and the additional conductive substrate,the overpotential at 10 mA cm^(-2)decreases to 250 mV,while the Tafel slope is reduced to 39 mV dec^(-1);these values indicate the as-prepared heterostructure is superior to the state-of-the-art MXene-based OER *** work provides a new strategy to enhance the OER activity of M_(n)X_(n-1)O_(2)and extends the application of LOM from perovskite to MXenes.