Fabrication of large-scale nanoporous nickel with a tunable pore size for energy storage

Abstract

Nanoporous Ni with a tunable nanopore size and chemical compositions was fabricated by dealloying a Ni30Mn70 precursor alloy at various temperatures. The influence of electrochemical parameters on the formation of large-scale nanoporous Ni was systematically investigated. Different from the fabrication of nanoporous noble metals (Au, Pt and Pd), the dealloying of Ni30Mn70 includes three kinetically competitive processes: dissolution of Mn, interface diffusion of Ni and dissolution of Ni. The nanopore size and residual Mn can be tailored by controlling the dealloying time, temperature and applied potential. The as-dealloyed nanoporous Ni with a large internal surface area, excellent conductivity and naturally formed oxide surface can be directly used as a free-standing electrode for electrochemical supercapacitors with a high capacitance and excellent cycling stability.

Bottom-up Synthesis of Porous NiMo Alloy for Hydrogen Evolution Reaction

“…Above 800 • C, the composition of NiMo (JCPDS #48-1745), Ni 4 Mo (JCPDS #65-5480), and pure Mo (JCPDS #42-1120) were gradually generated and oxidized species of NiO and MoO 2 were gradually reduced. It is worth noting that the reduction of NiMoO 4 requires 800 • C and reduction of MoO 2 requires 950 • C. Thus, the sample annealed at 950 • C only obtains NiMo with a certain amount of Ni 4 Mo alloys. In addition, an overview of XRD patterns of pristine NiMoO 4 and samples annealed at 400-950 • C is displayed in Figure S3.…”

“…It is worth noting that the reduction of NiMoO 4 requires 800 • C and reduction of MoO 2 requires 950 • C. Thus, the sample annealed at 950 • C only obtains NiMo with a certain amount of Ni 4 Mo alloys. In addition, an overview of XRD patterns of pristine NiMoO 4 and samples annealed at 400-950 • C is displayed in Figure S3. The specific surface area of the porous NiMo annealed at 950 • C was measured by the BET methods.…”

“…Recently, the study of nanoporous non-precious metals has been focused as electrodes and catalysts such as supercapacitors [3,4], Li-air batteries [5,6], fuel cells and water electrolysis [7,8], showing great potentials as precious metal-free electrodes. The fabrication process of nanoporous metals employs a dealloying method in which the solid solution alloy of precious metal and non-precious metal is electrochemically corroded in acidic electrolytes [1].…”

“…One of the most attractive porous metals is NiMo alloy which is known as one of the best hydrogen evolution electrode catalyst for cost-effective and highly efficient hydrogen production in water electrolysis [13,14]. Although different kinds of NiMo alloy porous morphologies were investigated such as HER catalysts including Ni 4 Mo [15], NiMo nanopowder [16], NiMo nanowire [17], the performances show that HER performance is not very enhanced due to the absence of bicontinuous and monolithic porous structures. Indeed, the Ni foam supported Ni 4 Mo nanoparticles, and the three-dimensional NiMo nanowires significantly improved their HER activities.…”

“…Although different kinds of NiMo alloy porous morphologies were investigated such as HER catalysts including Ni 4 Mo [15], NiMo nanopowder [16], NiMo nanowire [17], the performances show that HER performance is not very enhanced due to the absence of bicontinuous and monolithic porous structures. Indeed, the Ni foam supported Ni 4 Mo nanoparticles, and the three-dimensional NiMo nanowires significantly improved their HER activities. This means that bicontinuous and monolithic 3D electrode catalysts bring high reaction kinetics.…”