−60 °C solution synthesis of atomically dispersed cobalt electrocatalyst with superior performance

Abstract

Temperature can govern morphologies, structures and properties of products from synthesis in solution. A reaction in solution at low temperature may result in different materials than at higher temperature due to thermodynamics and kinetics of nuclei formation. Here, we report a low-temperature solution synthesis of atomically dispersed cobalt in a catalyst with superior performance. By using a water/alcohol mixed solvent with low freezing point, liquid-phase reduction of a cobalt precursor with hydrazine hydrate is realized at −60 °C. A higher energy barrier and a sluggish nucleation rate are achieved to suppress nuclei formation; thus atomically dispersed cobalt is successfully obtained in a catalyst for oxygen reduction with electrochemical performance superior to that of a Pt/C catalyst. Furthermore, the atomically dispersed cobalt catalyst is applied in a microbial fuel cell to obtain a high maximum power density (2550 ± 60 mW m−2) and no current drop upon operation for 820 h.

Engineering the Low Coordinated Pt Single Atom to Achieve the Superior Electrocatalytic Performance toward Oxygen Reduction

“…Different from the bulk morphology, it is discovered that Pt SAs can adsorb more than one atom or species. [8,15] Inspired by the difficulty in desorbing *OH from Pt SA as implied in mechanism I, the Pt SAs with one preadsorbed *OH is considered as the active site in boosting the ORR following pathway of mechanism II (Figure 5a). In the first step of mechanism II, an O 2 molecule adsorbs on the Pt SA with preadsorbed *OH can be converted into the intermediate of *OOH by reaction with a proton-electron pair (*OH + O 2 + (H + + e − ) to *OH + *OOH).…”

Recent Advances in Single-Atom Electrocatalysts for Oxygen Reduction Reaction

“…To be highlighted, this ice melting reduction method could be extended to fabricate other single-atom metal solutions including Co, Ni, Cu, Rh, Ru, Pd, Os, Ir, Pt, and Au. In a similar way, this liquid reduction method was used to prepare single-atom Co electrocatalyst (Co/NMC-LT900) at ultralow temperature of -60°C [47]. A CoCl 2 solution (Solution A) and an alkaline N 2 H 5 OH and KOH solution (Solution B) were cooled down to -60°C, respectively.…”

“…As shown in Figure 18(a), the current density (at 0.6 V) and peak power density reach 498 mA cm -2 and 0.38 W cm -2 , respectively, which are record high parameters among nonprecious metal electrocatalysts for AEMFCs. Another Fe-based SAEC by embedding Fe-N x moieties in the N-doped mesoporous carbon capsules (Fe-N-CC) provided an onset potential of 0.94 V (vs. RHE) and a half-wave potential of 0.83 V (vs. [47]. (e) Schematic illustration of the MFC.…”

A Thermal and Chemical Stable Graphene Derivative and Its Application as Bifunctional Oxygen Electrocatalyst

“…[64][65][66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81] (b) Comparison of ORR half wave potential of the reported single atomic electrocatalysts with Co-Ex-N2D. [42][43][44][45][46][47][48][49][50][51][52][53][54][55][56] Figure 6 | DFT calculations of ORR and OER process for Ex-N2D and Co-Ex-N2D electrocatalyst. (a) the free energy profile of ORR on Ex-N2D catalyst and the geometries of important structures along the pathway (b) the free energy profile of ORR on Co-Ex-N2D catalyst and the geometries of important structures along the pathway (c) HOMO/LUMO orbitals of Ex-N2D and Co-Ex-N2D catalyst.…”