MOF-Derived Noble Metal Free Catalysts for Electrochemical Water Splitting

Abstract

Noble metal free electrocatalysts for water splitting are key to low-cost, sustainable hydrogen production. In this work, we demonstrate that metal-organic frameworks (MOFs) can be controllably converted into catalysts for the oxygen evolution reaction (OER) or the hydrogen evolution reaction (HER). The OER catalyst is composed of FeNi alloy nanoparticles encapsulated in N-doped carbon nanotubes, which is obtained by thermal decomposition of a trimetallic (Zn, Fe, and Ni) zeolitic imidazolate framework (ZIF). It reaches 10 mA cm at the overpotential of 300 mV with a low Tafel slope of 47.7 mV dec. The HER catalyst consists of Ni nanoparticles coated with a thin layer of N-doped carbon. It is obtained by thermal decomposition of a Ni-MOF in NH. It shows low overpotential of only 77 mV at 20 mA cm with low Tafel slope of 68 mV dec. The above noble metal free OER and HER electrocatalysts are applied in an alkaline electrolyzer driven by a commercial polycrystalline solar cell. It achieves electrolysis efficiency of 64.4% at 65 mA cm under sun irradiation of 50 mW cm. This practical application shows the promising prospect of low-cost and high-efficiency sustainable hydrogen production from combination of solar cells with high-performance noble metal free electrocatalysts.

Mesoporous and Skeletal Molybdenum Carbide for Hydrogen Evolution Reaction: Diatomite‐Type Structure and Formation Mechanism

“…MoO x /DMF hybrid is collected after drying at 50 °C for a further 12 hours. MoO x /PPD hybrid is synthesized according to our previous method with PPD replacing aniline under the same conditions …”

“…These trials are designed to increase either the exposure of active sites or the conductivity of the whole architecture to improve the HER performance of electrocatalysts . For examples, various porous structures have been reported to be fabricated by either MOFs‐assisted, or biomass‐derived strategies, and a high specific surface area is usually declared to be achieved. However, most of the generated surface area is contributed from the existence of residual carbon rather than from the porous structure of the active phases themselves, and the relationship between the possible promotion on the HER and the veritable structure of active phases still remains deliberate.…”

Metal–Organic Framework Based Catalysts for Hydrogen Evolution

“…Apart from ZIF-67, other Co-based MOFs, [67,[118][119][120] ZIF-8, [121] MOF-74, [53,122] Ni 2 (bdc) 2 ted (bdc = 1,4-benzenedicarboxylic acid; ted = triethylenediamine), [123] other Ni-based MOFs [124] and bimetallic MOFs (such as NiZn-MOF (ted as organic linkers), [125] NiFe-MOF (bdc as organic linkers), [126] NiCo-MOF (bdc as organic linkers) [65] ) are demonstrated as effective precursors for the fabrication of various interesting metal compounds and metal/ carbon composites for electrocatalytic water splitting. …”

Design Strategies toward Advanced MOF‐Derived Electrocatalysts for Energy‐Conversion Reactions

“…[16] Currently, precious-metal-based catalysts (i.e., Ir, IrO 2 , and RuO 2 ) are the benchmark electrocatalysts for the OER. [15,16] Again, rationally designed materials derived from MOFs have been widely reported as alternative OER electrocatalysts, [35,80,[94][95][96]98,101,[113][114][115][116] and a summary of the OER performances of recent MOF-derived catalysts is listed in Table 2.…”

“…[98,101,106,[114][115][116] Among recent studies, Ahn and co-workers' report is one of the highest bifunctional catalysts for water electrolysis. [106] As presented in Figure 15a, a typical two-step approach was employed to derive carbon-incorporated porous Ni-Fe-P nanorods grown on nickel foams (porous NiFeP@C).…”