Search

Hierarchical Cu−Sn core/shell nanowire arrays were built on 3‐dimensional macroporous Ni foams through a two‐step deposition, annealing, and electroreduction treatment. Cu was electroplated on Ni foam substrates and the sample was annealed at 500 °C followed by electroreduction, producing Cu nanowires of 150 nm diameter in arrays on the skeleton of Ni foams. Sn nanoparticles of 14–80 nm were then chemically deposited on Cu nanowires in clusters and a second annealing treatment at 200 °C followed by electroreduction re‐organized the clusters into a SnxO/Sn shell of 8 nm thickness. Creating such a Sn shell on Cu nanowires suppressed faradaic efficiencies for H2 evolution from 55.7 to 10.1 % and for HCOOH formation from 13.2 to 2.0 % and enhanced CO generation from 32.0 to 90.0 % at an applied potential of −0.8 V (vs. RHE). The faradaic efficiency for CO production remained almost constant at 90.0–91.4 % with total current densities of −13.2 to −19.3 mA cm−2 between −0.8 and −1.2 V (vs. RHE). Array of sunshine: A double deposition‐annealing treatment created hierarchical Cu−Sn core/shell nanowire arrays on Ni foam, which can achieve high‐performance CO2 reduction. [ABSTRACT FROM AUTHOR]

Nickel/iron (Ni−Fe)-based compounds are known as active electrocatalysts for the oxygen evolution reaction (OER), which plays an important role in metal−air batteries and water splitting. Herein, a three-dimensional (3D) porous nickel foam electrode (NiFe(OH) x NSs/Nif) modified with Ni−Fe hydroxide nanosheets (NSs) is prepared by using a fast and facile electrodeposition method. The electrode is subsequently applied in the electrolysis of Na2CO3/NaHCO3 to produce hydrogen, oxygen, NaOH, and NaHCO3/CO2. By carefully controlling the electrodeposition time, ultrathin NiFe(OH) x NSs with a thickness of approximately 2-6 nm are interlaced with one another and grown vertically on nickel foam to form a hierarchical composite electrode. The prepared NiFe(OH) x NSs/Nif electrode exhibits superb OER performance with an overpotential of 260 mV at 10 mA cm−2 and a low Tafel slope of 29 mV dec−1 in 1 mol L−1 NaOH solution. In 0.5 mol L−1 Na2CO3/NaHCO3 solution, the NiFe(OH) x NSs/Nif electrode exhibits a low OER potential of 290 mV, which is lower than the commercial RuO2/Ti electrode at a current density of 100 mA cm−2, and shows good long-term stability. During electrolysis of Na2CO3/NaHCO3, the cell voltage with the NiFe(OH) x NSs/Nif anode is 2.52 V, which is 280 mV lower than that with a commercial RuO2/Ti anode. [ABSTRACT FROM AUTHOR]

Developing oxygen reduction reaction (ORR) catalysts with high activity and low cost is a challenge in the field of electrochemical energy conversion. Here, an efficient catalyst of N-doped carbon with non-precious metals (Mn, Fe, Co, and Ni) designated as MFCN/NC has been prepared by using a simple pyrolysis method. Pyridinic nitrogen, graphitic carbon, MnO, and Fe-Co-Ni nanoparticles, which are efficient for catalyzing the ORR individually or synergistically, are successfully introduced into the composite catalyst. The optimized MFCN/NC catalyst exhibits four-electron reduction of O2 with a more positive ORR onset potential (54 mV) and a more positive half-wave potential (46 mV) than commercial Pt/C. Moreover, MFCN/NC shows remarkable electrocatalytic activity and long-term stability in Na2CO3 electrolysis. The cell voltages at 10 and 100 mA cm−2 are only 0.86 and 1.45 V, respectively, suggesting an energy-saving electrolysis of Na2CO3 to regenerate NaHCO3 and NaOH. [ABSTRACT FROM AUTHOR]