Yi-Ming Yan

A bulky and flexible electrocatalyst for efficient hydrogen evolution based on the growth of MoS2 nanoparticles on carbon nanofiber foam

An advanced hydrogen evolution reaction (HER) electrocatalyst is highly desired for the development of solar water-splitting devices. In this work, we describe the preparation of a flexible, three-dimensional (3D) and durable electrode, which is composed of MoS2 nanoparticles grown on bacteria-cellulose-derived carbon fiber foam (MoS2/CNF). The MoS2/CNF foam was used as a bulky and flexible HER electrocatalyst, exhibiting excellent catalytic activity for a hydrogen evolution reaction in an acidic electrolyte (16 mA cm−2 at an overpotential of 230 mV). Remarkably, this novel HER electrocatalyst shows a low onset overpotential of 120 mV, a small Tafel slope of 44 mV dec−1, a high exchange current density of 0.09 mA cm−2, and a Faradaic efficiency of nearly 100%. This work offers an attractive strategy of preparing bulky and flexible electrocatalyst for large-scale water splitting technology.

Diethylenetriamine (DETA)-assisted anchoring of Co3O4 nanorods on carbon nanotubes as efficient electrocatalysts for the oxygen evolution reaction

A Co3O4 nanorod–multiwalled carbon nanotube hybrid (Co3O4@MWCNT) has been fabricated as a highly efficient electrocatalyst for water oxidation in alkaline electrolytes. The well-defined Co3O4 nanorods were successfully anchored onto mildly oxidized MWCNTs with the assistance of diethylenetriamine (DETA) following a simple route. The as-prepared hybrid possesses a promising BET specific surface area of about 252 m2 g−1 and shows excellent electrocatalytic activity towards oxygen evolution reactions (OERs) with an onset potential of about 0.47 V vs. Ag/AgCl and an overpotential of 309 mV to achieve a current density of 10 mA cm−2 in 1.0 mol L−1 KOH. In addition, the Co3O4@MWCNT catalyst exhibits prominent stability during long-term electrolysis of water. We attribute the enhanced performance to a synergic effect between MWCNTs and Co3O4 nanorods by gaining insight into the electrochemical properties of the Co3O4@MWCNT hybrid. This work offers a useful way to synthesize one-dimensional (1D) metal oxides combined with 1D carbon materials for wide applications in energy storage and conversion.

Templated-preparation of a three-dimensional molybdenum phosphide sponge as a high performance electrode for hydrogen evolution

Electrocatalysts play a vital role in electrochemical water-splitting for hydrogen production. Here, we report the preparation of three-dimensional molybdenum phosphide (MoP) as a non-precious-metal electrocatalyst for the hydrogen evolution reaction (HER) by using cheap sponge (polyurethane, PU) as a sacrificial template. The obtained 3D MoP not only has large surface area, but also possesses a porous and channel-rich structure, in which the side walls of the pores are composed of refined nanoparticles. The 3D MoP sponge was used as a bulky and binder-free HER electrode and exhibited excellent catalytic activity in an acidic electrolyte (achieving 10 and 20 mA cm−2 at an overpotential of 105 and 155 mV, respectively). In addition, this novel bulky HER electrode showed a relatively small Tafel slope of 126 mV dec−1, a high exchange current density of 3.052 mA cm−2, and a faradaic efficiency of nearly 100%. Furthermore, this bulky electrode revealed high tolerance and durability both under acidic and basic conditions, maintaining 96% and 93% of its initial catalytic activity after continuous testing for 60 000 s. Thus, our work paves a feasible way of fabricating a cheap and highly efficient HER electrode on a large-scale for electrochemical water-splitting technology.

Synthesis of MoP decorated carbon cloth as a binder-free electrode for hydrogen evolution

Electrocatalysts play a vital role in electrochemical water-splitting for hydrogen production. However, searching for low-cost and earth-abundant electrocatalysts remains a challenge. In this study, we report the synthesis of mesoporous molybdenum phosphide hemispheres as electrocatalysts and their direct growth on a carbon cloth (MoP-HS@CC) to create a self-supported electrode for efficient hydrogen evolution. The obtained MoP-HS@CC was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and nitrogen adsorption–desorption. MoP-HS@CC not only has a large surface area, it also possesses rich porosity. In addition, as a binder-free electrode for hydrogen evolution, MoP-HS@CC exhibits a low onset overpotential of 30 mV, a small Tafel slope of 61 mV dec−1, and a large exchange current density of 0.438 mA cm−2 in acidic electrolytes. It affords current densities of 10 and 100 mA cm−2 at overpotentials of 87 and 195 mV, respectively. Moreover, MoP-HS@CC shows a strong tolerance to working environment both in acidic and alkaline conditions. This study essentially offers a simple and viable strategy for preparing highly efficient and flexible electrodes on a large-scale for electrochemical water-splitting technology.

Preparation of porous reduced graphene oxide using cellulose acetate for high performance capacitive desalination

A three-dimensional porous graphene electrode is prepared by using cellulose acetate as a sacrifice template. The electrode possesses an ideal porous structure and large surface area, therefore resulting in a high electrosorption capacity for CDI application.