High-throughput production of cheap mineral-based two-dimensional electrocatalysts for high-current-density hydrogen evolution

Abstract

The high-throughput scalable production of cheap, efficient and durable electrocatalysts that work well at high current densities demanded by industry is a great challenge for the large-scale implementation of electrochemical technologies. Here we report the production of a two-dimensional molybdenum disulfide-based ink-type electrocatalyst by a scalable exfoliation technique followed by a thermal treatment. The catalyst delivers a high current density of 1000 mA cm^-2 at an overpotential of 412 mV for the hydrogen evolution. Using the same method, we produce a cheap mineral-based catalyst possessing excellent performance for high-current-density hydrogen evolution. Noteworthy, production rate of this catalyst is one to two orders of magnitude higher than those previously reported, and price of the mineral is five orders of magnitude lower than commercial Pt electrocatalysts. These advantages indicate the huge potentials of this method and of mineral-based cheap and abundant natural resources as catalysts in the electrochemical industry.

Fig. 1. High-throughput production of molybdenum disulfide (MoS₂)-based ink-type electrocatalysts.

a Schematic of the fabrication method of MoS₂-based catalysts. b Scanning electron microscopy image of the pristine MoS₂ powder, and photos of (c) two-dimensional (2D) MoS₂ aqueous dispersion with a volume of 60 liters, (d) bare copper (Cu) foam and (e) MoS₂-based catalyst loaded on Cu foam.

Fig. 2. Material characterization.

a Atomic force microscopy image and statistical analysis of (b) the lateral size and c the thickness of the 2D MoS₂ flakes. d High resolution transmission electron microscopy (HRTEM) image of the 2D MoS₂. Inset is the corresponding fast Fourier transform (FFT) pattern. e HRTEM image of the HC-MoS₂/Mo₂C. The insets are a histogram of the lateral size of the Mo₂C nanocrystals, and two high magnification HRTEM images of a MoS₂ flake (the blue dotted box) and a Mo₂C nanocrystal (the red dotted box). The scale bars in the insets are 1 nm. f X-ray diffraction pattern and (g) Raman spectra of the 2D MoS₂ and the HC-MoS₂/Mo₂C.

Fig. 3. Electrocatalytic performance of different catalysts for high-current-density HER.

a Polarization curves, (b) Tafel plots, and (c) Δη/Δlog|j | ratios of different catalysts in 0.5 M H₂SO₄ at a scan rate of 5 mV s⁻¹ with iR correction. d Photos and (e) corresponding size distribution of H₂ bubbles leaving the surfaces of HC-MoS₂/Mo₂C catalysts. f A comparison of the HER performance of HC-MoS₂/Mo₂C catalysts and Pt-based catalysts we tested and previously reported (see details in Supplementary Table 2). The “w/o iR corr.” and “with iR corr.” in (f) mean without and with iR correction. g Chronoamperometric response (i–t) curves for hydrogen evolution reaction (HER) using HC-MoS₂/Mo₂C at current densities of 200 and ~500 mA cm⁻² for 24 h, corresponding to potentials of −360 and −400 mV vs reversible hydrogen electrode (RHE) without iR correction. The error bars show the standard derivation in (c) and (d).

Fig. 4. MoS₂ mineral catalysts from cheap molybdenite concentrates for high-current-density HER.

a Bird’s eye view of the Sandaozhuang open-pit molybdenite mine in Luoyang, China. Reproduced from Ref. . The length of the field is around 1.5 km. b Commodity price differences between platinum, high-purity MoS₂, industrial-grade MoS₂, and molybdenite concentrate. c Polarization curves of the different catalysts in 0.5 M H₂SO₄ at a scan rate of 5 mV s⁻¹ with iR correction. Inset is an optical image of a three-electrode electrolyzer for larger working electrodes. d H₂ production rate of different molybdenite concentrate-based catalysts to produce hydrogen under −390 mV vs RHE without iR correction. e Chronoamperometric response (i–t) curve of a 5 cm² roll of cheap mineral-based catalyst for HER at current of ~500 mA over 24 h.

Fig. 5. High-efficiency and low-cost production of MoS₂ mineral-based catalysts from cheap molybdenite concentrate for high-current-density HER.

a A comparison of the fabrication rate and highest tested current density of transition metal dichalcogenide-based HER catalysts by different methods. Details for data points are shown in Supplementary Table 1. b A comparison of the catalyst cost compared to commercial electrocatalysts for HER, showing the ultralow cost of the HC-MoS₂/Mo₂C catalyst. Note that the support costs of HC-MoS₂/Mo₂C, Raney Ni, Pt and Pt/C catalysts are excluded.