The modulating of the geometric and electronic structures
of metal–N–C
atomic catalysts for improving their performance in catalyzing oxygen
reduction reactions (ORRs) is highly desirable yet challenging. We
herein report a delicate “encapsulation–substitution”
strategy for the synthesis of paired metal sites in N-doped carbon.
With the regulation of the d-orbital energy level,
a significant increment in oxygen electroreduction activity was demonstrated
in Ru–Co diatomic catalyst (DAC) compared with other diatomic
(Ru–Fe and Ru–Ni) and single-atomic counterparts. The
Ru–Co DAC efficiently reduces oxygen with a halfwave potential
of 0.895 V vs RHE and a turnover frequency of 2.424
s–1 at 0.7 V, establishing optimal thermodynamic
and kinetic behaviors in the triple-phase reaction under practical
conditions. Moreover, the Ru–Co DAC electrode displays bifunctional
activity in a gas diffusion Zn–air battery with a small voltage
gap of 0.603 V, outperforming the commercial Pt/C|RuO2 catalyst.
Our findings provide a clear understanding of site-to-site interaction
on ORR and a benchmark evaluation of atomic catalysts with correlations
of diatomic structure, energy level, and overall catalytic performance
at the subnanometer level.
Metal promotion is the most widely adopted strategy for enhancing the hydrogenation functionality of an oxide catalyst. Typically, metal nanoparticles or dopants are located directly on the catalyst surface to create interfacial synergy with active sites on the oxide, but the enhancement effect may be compromised by insufficient hydrogen delivery to these sites. Here, we introduce a strategy to promote a ZnZrOx methanol synthesis catalyst by incorporating hydrogen activation and delivery functions through optimized integration of ZnZrOx and Pd supported on carbon nanotube (Pd/CNT). The CNT in the Pd/CNT + ZnZrOx system delivers hydrogen activated on Pd to a broad area on the ZnZrOx surface, with an enhancement factor of 10 compared to the conventional Pd-promoted ZnZrOx catalyst, which only transfers hydrogen to Pd-adjacent sites. In CO2 hydrogenation to methanol, Pd/CNT + ZnZrOx exhibits drastically boosted activity—the highest among reported ZnZrOx-based catalysts—and excellent stability over 600 h on stream test, showing potential for practical implementation.
End-of-life lithium-ion batteries (LIBs) constitute an "urban mine" that offers a great opportunity to repurpose the metal species. However, the direct and cross-domain reuse of their functional materials has been ignored. Herein, we report a case study of upcycling a LIB cathode, LiFePO 4 particles embedded in N-doped carbon spheres (LFP/C), to a single-atomic (SA) electrocatalyst for the oxygen reduction reaction (ORR). Using a top-down leaching method, the LFP/C was converted to Fe SA-embedded hollow carbon spheres containing minor FeO x nanoclusters and FePO 4 nanoparticles (SA Fe /FeO x /FePO 4 ). Our studies indicate that the neighboring FeO x /FePO 4 modulate the electronic filling in the antibonding state of SA Fe sites and thereby optimize the intermediate adsorption energy at the rate-determining step, leading to the boosted half-cell ORR activity as manifested by a high E onset of 0.97 V. Furthermore, the membrane electrode fabricated with the SA Fe /FeO x /FePO 4 demonstrates great potentials in two practical energy conversion devices, an ammonia fuel cell and Zn-air battery, building a bridge across the energy applications.
The aim of this research was to analyse football tournaments, UEFA Euro 2021 and Copa America 2021, to provide statistical measurement to predict which teams were likely to be qualified to the next round in the knockout stage. The research method used to collect six key variables statistics including total attempts, on target, possession, passes attempted, passing accuracy, and corners taken from 79 matches in UEFA Euro 2021 and Copa America 2021. The data were analysed by the grey relational analysis (GRA). The results were as follows: first, this study presented variables related to goals scored and offense correlated on goals scored. Second, this study proposed a GRA model that provides an efficient way to predict match outcomes. Third, the GRA model will perform better than the FIFA world ranking when more teams participated and the world ranking were tight.
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