Cobalt decorated ultra-thin Ti₃C₂ MXene electrocatalyst for high-efficiency hydrogen evolution reaction

The spindle ultra-thin Ti₃C₂ MXene nanotablets are successfully fabricated by high energy ultrasonic wave treatment. The as-prepared Ti₃C₂ are terminated with =O, −OH or/and −F groups. The Co nanoparticles are bonded with Ti₃C₂ nanotablets and form Ti₃C₂(O_2-xH_2-x-2mF_xCo_m) hybrid by refluxing approach. Zeta potential measurement illustrates that the Co nanoparticles carry positive charge while the Ti₃C₂ nanotablets carry negative charge, implying that there is a transfer path of electron density from Co nanoparticles to Ti₃C₂ nanotablets. As a result, the Co acts as the hydride-acceptor and Ti₃C₂ acts as the proton-acceptor in Co-Ti₃C₂ hybrid. Compared with Co nanoparticles and Ti₃C₂ nanotablets, the Co-Ti₃C₂ hybrid exhibites low overpotential, low Tafel plot and high electrocatalytic property. The introduction of Co nanoparticles can effectively enhance the conductivity of bulk Ti₃C₂ and accelerate the charge transfer rate between Co and Ti₃C₂, which are beneficial for the electrocatalytic performance. (paper)