Potent Charge‐Trapping for Boosted Electrocatalytic Oxygen Reduction

Abstract

Metal‐free carbon‐based materials are considered to be one of the most promising alternatives to precious metal Pt‐based electrocatalysts. However, the electrocatalytic activity of heteroatom‐modulated carbon rarely reaches the level of metal‐based electrocatalysts. Here, electron‐rich carbon and abundant pyridinic‐N adjacent to C vacancies decorated with carbon nanosheets (E‐NC‐V) are synthesized and used as the host for boosting efficient oxygen reduction reaction. Rich pyridinic‐N structures adjacent to C vacancies work in synergy with electron‐rich carbon, which promotes the sharp decrease of |ΔGO*|, resulting in the balanced adsorption and dissociation of oxygen intermediates, and thus activating OO. This can be attributed to the abundant vacancies and d–p orbital hybridization between Zn and N/C. The E‐NC‐V catalyst drives the oxygen reduction reaction (ORR) via a 4e− transfer‐dominated pathway with a half‐wave potential of 0.87 V versus RHE in the alkaline solution, even superior to Pt/C. The assembled Al–air battery exhibits a high peak power density of 113 mW cm−2. This promising strategy sheds light on the design and fabrication of robust, rich‐density, and high‐performance active sites for the ORR. The work is expected to inspire future work on the role of electronic structure modulation and defect engineering for enhanced reaction kinetics.

High-loading As single-atom catalysts harvested from wastewater towards efficient and sustainable oxygen reduction

“…6 Most non-precious metal catalysts exhibit much less ORR performance in 0.1 M HClO 4 than in 0.1 M KOH. 10,11,23,34 As-DC1-1050 exhibits an E 1/2 of 0.77 V in 0.1 M HClO 4 , further validating the utility of As-DC1-1050 in different electrolytes (Fig. S14, ESI†).…”

“…The competition reactions between the two-electron and four-electron pathways inhibit its four-electron activity, resulting in a lower E 1/2 . 17,34 In addition, As-DC1-1050 exhibits a Tafel slope of 65 mV dec −1 which is less than the 76 mV dec −1 of 20% Pt/C, indicating that As-DC1-1050 demonstrates comparable ORR kinetics to noble metal catalysts (Fig. 4d).…”

“…Volatilization of Zn above 900 °C contributed to various carbon defects such as pentagonal, heptagonal, etc. 10,11,34 (Fig. S1, ESI†).…”

Manipulation of Electronic States of Pt Sites via d-Band Center Tuning for Enhanced Oxygen Reduction Reaction in Proton Exchange Membrane Fuel Cells

“…As neotype ORR electrocatalysts, atomically dispersed Pt–nitrogen–carbon (Pt–N–C) sites have been demonstrated to have unique physicochemical properties contributing to various electrochemical reactions in energy storage and conversion due to their maximum atom utilization efficiency, capability of remarkably reducing Pt usage, and excellent electrocatalytic activity. − However, the degradation of the catalytic performance of these reported Pt–N–C under long-term operation is still behind satisfactory for ORR. As an effective and reasonable strategy, the combination of metal nanoparticles and single atoms can adjust the electronic orbital of metal-N active sites, help O 2 activation on metal-N active sites through shifting the location of the d-band center of Pt, and lead to optimized adsorption binding energies between Pt and reaction oxygen-related intermediates during the ORR process. − Currently, covalent organic frameworks (COFs) are one type of burgeoning crystalline porous polymers with framework designability and precise structural tenability, which provides a unique advantage in the fabrication of materials derived from the distinct electronic configurations of in situ formed exotic metal species coordinated to N atoms. − In addition, from the perspective of functional materials, COF-derived N–C materials with a uniform M–N center and a nanosized porous channel in the carbon substrate are highly appealing in the field of heterogeneous catalysis. − With this knowledge, a question arises: whether it is conceivable to modulate the Pt site electronic environment through altering the d-band centers with Pt particles and an atomically dispersed state in the COF-derived porous nanocarbon matrix. − Moreover, it is of great theoretical and practical importance to research the corresponding reaction mechanism of the ORR process on this issue and apply it practically in PEMFCs.…”

Effect of the N,S-Codoped Carbon Layer on the Rate Performance of Air-Stable Lithium Iron Oxide Prelithiation Additives

“…With worldwide attention to developing new energy storage devices, lithium-ion batteries have developed rapidly due to their excellent cycling performance and high specific capacity. − Prelithiation technology (PLT) is an effective means to introduce additional lithium sources to make up for the Li depletion from the formation of a solid–electrolyte interphase layer on the anode during first cycles. − PLT can be generally divided into cathode prelithiation technology (CPL) and anode prelithiation technology (APL). On the one hand, chemical, electrochemical, and additive-assisted approaches are common APL technologies. − However, APL is currently faced with many hazardous issues such as an uneven degree of lithiation, poor environmental suitability, and inferior safety, which impede its large-scale use in the industry.…”