Dongping Xue

) reduction (ECR) has become one of the main methods to close the broken carbon cycle and temporarily store renewable energy, but there are still some problems such as poor stability, low activity, and selectivity. While the most promising strategy to improve ECR activity is to develop electrocatalysts with low cost, high activity, and long-term stability. Recently, defective carbon-based nanomaterials have attracted extensive attention due to the unbalanced electron distribution and electronic structural distortion caused by the defects on the carbon materials. Here, the present review mainly summarizes the latest research progress of the construction of the diverse types of defects (intrinsic carbon defects, heteroatom doping defects, metal atomic sites, and edges detects) for carbon materials in ECR, and unveil the structure-activity relationship and its catalytic mechanism. The current challenges and opportunities faced by high-performance carbon materials in ECR are discussed, as well as possible future solutions. It can be believed that this review can provide some inspiration for the future of development of high-performance ECR catalysts.

Precise tuning of the chemical environment of neighboring atomic FeN4 sites is extremely important for optimizing Fe–N–C catalysts to produce the fast oxygen reduction reaction (ORR) kinetics both in acidic and alkaline media, but it is actually very challenging. Heteroatoms could affect the metal charge of the active center through long-range electron delocalization; however, there are a few studies on it. Herein, density functional theory (DFT) calculations demonstrate that the addition of long-range P into edge-type FeN4 can drive the electron delocalization and decrease the band gap of the FeN4 center, leading to a substantial decrease in the free energy barrier to direct four-electron ORR kinetics compared to P-free edge-type FeN4, indicating superior intrinsic ORR activity. Experimentally, by incorporating P in edge-rich FeN4 supported on N,P-doped carbon (Fe–N–C–P/N,P–C), the created Fe–N–C catalyst presents the greatly increased acidic ORR activity, with a half-wave potential (E1/2) of 0.80 V (vs a reversible hydrogen electrode), which approaches that of commercial Pt/C and also has a high half-wave potential of 0.87 V, beyond Pt/C for alkaline ORR. In addition, it shows higher proton exchange membrane fuel cell and Zn-air battery performances than the pristine Fe–C–N catalyst (Fe–N–C/N–C). This work will guide the rational design of highly active metal atomic scale catalysts with optimized chemical surroundings in terms of P incorporation as a chemically tunable method.

Abstract Efficient oxygen evolution reaction electrocatalysts are essential for sustainable clean energy conversion. However, catalytic materials followed the conventional adsorbate evolution mechanism (AEM) with the inherent scaling relationship between key oxygen intermediates *OOH and *OH, or the lattice-oxygen-mediated mechanism (LOM) with the possible lattice oxygen migration and structural reconstruction, which are not favorable to the balance between high activity and stability. Herein, we propose an unconventional Co-Fe dual-site segmentally synergistic mechanism (DSSM) for single-domain ferromagnetic catalyst CoFeS x nanoclusters on carbon nanotubes (CNT) (CFS-ACs/CNT), which can effectively break the scaling relationship without sacrificing stability. Co 3+ (L.S, t 2g 6 e g 0 ) supplies the strongest OH* adsorption energy, while Fe 3+ (M.S, t 2g 4 e g 1 ) exposes strong O* adsorption. These dual-sites synergistically produce of Co-O-O-Fe intermediates, thereby accelerating the release of triplet-state oxygen ( ↑ O = O ↑ ). As predicted, the prepared CFS-ACs/CNT catalyst exhibits less overpotential than that of commercial IrO 2 , as well as approximately 633 h of stability without significant potential loss.

Abstract Disentangling the limitations of O-O bond activation and OH* site-blocking effects on Pt sites is key to improving the intrinsic activity and stability of low-Pt catalysts for the oxygen reduction reaction (ORR). Herein, we integrate of PtFe alloy nanocrystals on a single-atom Fe-N-C substrate (PtFe@Fe SAs -N-C) and further construct a ferromagnetic platform to investigate the regulation behavior of the spin occupancy state of the Pt d -orbital in the ORR. PtFe@Fe SAs -N-C delivers a mass activity of 0.75 A mg Pt −1 at 0.9 V and a peak power density of 1240 mW cm −2 in the fuel-cell, outperforming the commercial Pt/C catalyst, and a mass activity retention of 97%, with no noticeable current drop at 0.6 V for more than 220 h, is attained. Operando spectroelectrochemistry decodes the orbital interaction mechanism between the active center and reaction intermediates. The Pt dz 2 orbital occupation state is regulated to t 2g 6 e g 3 by spin-charge injection, suppressing the OH* site-blocking effect and effectively inhibiting H 2 O 2 production. This work provides valuable insights into designing high-performance and low-Pt catalysts via spintronics-level engineering.