A Single Source, Scalable Route for Direct Isolation of Earth-Abundant Nanometal Carbide Water-Splitting Electrocatalysts

Abstract

Single-phase M x Cs (M = Fe, Co, and Ni) were prepared by solvothermal conversion of Prussian blue single source precursors. The single source precursor is prepared in water, and the conversion process is carried out in alkylamines at reaction temperatures above 200 °C. The reaction is scalable using a commercial source of Fe-PB. High-resolution transmission electron microscopy, X-ray photoelectron microscopy, and powder X-ray diffraction confirm that carbides have thin oxide termination but lack graphitic surfaces. Electrocatalytic activity reveals that Fe3C and Co2C are oxygen evolution reaction electrocatalysts, while Ni3C is a bifunctional [OER and hydrogen evolution reaction (HER)] electrocatalyst.

Electrocatalytic activity and surface oxide reconstruction of bimetallic iron–cobalt nanocarbide electrocatalysts for the oxygen evolution reaction

“…The monometallic Co carbide was shown to not have a notable increase in crystalline oxide before and after 30 CV cycles and maintained robust electrochemical stability. 22 Therefore, we can infer that the initial electrochemical instability in the first 30 CV cycles we observe in the FeCo nanocarbide (15% Fe) resulted from rapid surface oxide formation. To enhance our understanding of the rapid surface reconstruction of 100% carbide to 57% spinel oxide (43% carbide) coverage in the nanomaterial after 160 CV cycles, we further analyzed how much total oxide contributed to the surface layer of the nanoparticle.…”

Metal Carbide Nanocrystal Nucleation and Growth in a Transition Metal Coordination Polymer

“…It was reported previously that alkylamine-assisted thermal decomposition Co-PBA leads to the isolation of Co 2 C; however, the mechanism of growth was not analyzed. In Figure , the transition from PBA (PDF# 01-077-1161, Fm -3 m ) to Co 2 C (PDF# 01-072-1369, Pmnn ) is shown for the reaction carried out at 217 and 330 °C.…”

“…The recently reported transformation of a Prussian blue analogue (PBA) mesocrystal to metal carbide nanocrystal is an ideal case study for evaluating solid state transformation nucleation and growth . While isolated metal carbides have been shown to be nanocrystals and are catalytically active, the growth mechanism is poorly understood. ,− It was hypothesized that the growth mechanism to form the carbide nanocrystal follows a stepwise transformation initiated by amine attack at (111) corners with propagation along (100), (010), and (001) at defects, including glide plane lattice defects, vacancies, and delaminated surfaces . It is reasonable to assume the formation of the metal carbide from the mesocrystal template can be described by nucleation theory, albeit with the constraint that for nucleation to occur, the loss of cyanamide (NCN) is required.…”

“…Solution processable nanocrystals can be prepared by a variety of techniques, including traditional hot-injection colloidal methods, ball milling, sol–gel decomposition, gas phase condensation, and templating from a solid-state mesocrystal. , Using crystallization models, the nucleation and growth dynamics can be described in a variety of nanocrystal reactions. − through a plethora of models, including classical nucleation theory (high monomer conditions), the Avrami model (slow nucleation/fast growth), − and the autocatalytic Finke–Watzky (FW) model (subsaturation monomer conditions). In all models for describing solution growth from monomers, nucleation is the critical step and growth is controlled by monomer availability with the difference being in the rate of growth versus nucleation.…”

New Avenues to Chemical Space for Energy Materials by the Molecular Precursor Approach

“…The electrocatalysts were tested for alkaline OER and acidic HER but only Ni 3 C showed good activity as an amphoteric electrocatalyst for water-splitting but remained less active compared to literature ref. [120] Not long ago, Revaprasadu et al in 2021 used a molecular precursor of bismuth (tris(selenobenzoato)bismuth(III), [Bi(SeOCPh) 3 ]), to prepare selectively Bi or Bi 2 Se 3 nanosheets. The Bi 2 Se 3 nanosheets were received by injecting the [Bi(SeOCPh) 3 ] complex dispersed in 1-octadecene, into oleylamine preheated at 200 °C while pure Bi was attained when trioctylphosphine was used instead of 1-octadecene.…”