A Compatible and Efficient Fabrication of Bi-Continuous Nanoporous Copper Films

To cater to the application in various micro/nano devices, this paper reports a compatible and efficient approach combining electrodeposition and dealloying to fabricate bi-continuous nanoporous copper films. In the electrodeposition step, effect of concentration ratio of different ions, pH of the solution and cathode current density on the elementary composition and microscopic morphology of the deposited alloy are systematically investigated, obtaining an optimum condition with good stability and process compatibility. A uniform copper-zinc alloy with its zinc content improved to ~67 at.% is prepared under this condition. A uniform nanoporous copper with an average pore size of 150 nm is fabricated by ultrasonic assisted dealloying whose efficiency is significantly improved compared to free dealloying. This method is promising to be used in the mass production of nanoporous copper films, benefiting researches on various practical applications in micro/nano devices.

PPy coated nanoflower like CuCo2O4 based on in situ growth of nanoporous copper for high-performance supercapacitor electrodes

General CuCo2O4 electrodes suffer a very low reversible capacity and poor cycling stability because of easily fading phenomena and volume change during cycling. To optimize the electrode, a facile method is conducted to fabricate a novel electrode of Cu@CuCo2O4@polypyrrole (Cu@CCOP) nanoflowers. Due to larger specific surface area and more electrochemical reactive areas of Cu@CCOP nanoflowers, the pseudocapacitance of the in-situ grown Cu@CCOP (912 F g-1 at 2 A g-1) is much higher than the pristine CuCo2O4 (CCO) (618 F g-1 at 2 A g-1). Remarkably, the Cu@CCOP (cathode) and active carbon (anode) are used to assemble an asymmetric supercapacitor, which exhibits a relatively high energy density of 90 Wh kg-1 at a power density of 2519 W kg-1 and 35 Wh kg-1 at a high-power density of 9109 W kg-1, and excellent cycling stability (about 90.4% capacitance retention over 10000 cycles). The prominent performance of Cu@CCOP makes it as a potential electrode for supercapacitor.

Degradation performance and mechanism toward methyl orange via nanoporous copper powders fabricated by dealloying of ZrCuNiAl metallic glassy precursors

The catalyst of nanoporous Cu (NP-Cu) powders, with the chemical composition of Cu79.63Ni6.85O13.53 (at.%), was successfully fabricated by dealloying of Zr-Cu-Ni-Al metallic glassy precursors. The as-prepared NP-Cu powders, co-existing with Cu2O phase on Cu ligament surface, had a three-dimensional (3D) network porous structure. The NP-Cu powders/H2O2 system showed superior catalytic degradation efficiency toward azo dyes in both acidic (pH 2) and neutral (pH 7) environments. Moreover, the cyclic tests indicated that this powder catalyst also exhibited good durability. A novel degradation mechanism of NP-Cu powders/H2O2 was proposed: the high degradation performance in acidic environment was mainly derived from heterogeneous reaction involved with a specific pathway related to Cu3+ to produce HO•, while in neutral environment it was primarily resulted from homogeneous reaction with the generation of HO• from the classical Cu-based Fenton-like process. This work indicates that the NP-Cu powders have great potential applications as catalysts for wastewater treatments.

Effect of Dealloying Time and Post-Annealing on the Surface Morphology and Electrocatalytic Behavior of Nanoporous Copper Films for CO2 Reduction Reaction

Electrocatalytic reduction reaction of CO2 (CO2RR) is one of the promising routes to mitigate global warming via transforming greenhouse gas into valuable chemical feedstocks. By adding proper electrocatalysts, such as nanoporous copper (NPC) with an average ligament size of 37 ± 6 nm, hydrocarbons could be produced at a relatively low overpotential. As the dealloying time increased to 156 hrs, the NPC was transformed into CuO nanosheet structure, which yielded larger electrochemical surface area (ECSA) and current density than the as-prepared NPC films. However, the Faraday efficiency (FE) of the major conversion product, formic acid (HCOOH), decreased from 29 to 8% when the nanosheet structure was used as electrocatalyst. On the other hand, the surface morphology of the NPC films remained similar while the average ligament size increased from 37 to 63 nm after a post-annealing treatment at 500 °C for 4 hrs. Both the current density and ECSA of this post-annealed NPC film were nearly 3 times higher than those of as-prepared NPC film, and the FE toward HCOOH increased from 29 to 45%. X-ray photoelectron spectroscopy and Raman spectroscopy revealed that Cu2O were present on the nanoporous structure, which enhanced the selectivity and FE toward HCOOH in CO2RR.