Formation of Hierarchical Structure Composed of (Co/Ni)Mn-LDH Nanosheets on MWCNT Backbones for Efficient Electrocatalytic Water Oxidation

Active, stable, and cost-effective electrocatalysts are attractive alternatives to the noble metal oxides that have been used in water splitting. The direct nucleation and growth of electrochemically active LDH materials on chemically modified MWCNTs exhibit considerable electrocatalytic activity toward oxygen evolution from water oxidation. CoMn-based and NiMn-based hybrids were synthesized using a facile chemical bath deposition method and the as-synthesized materials exhibited three-dimensional hierarchical configurations with tunable Co/Mn and Ni/Mn ratio. Benefiting from enhanced electrical conductivity with MWCNT backbones and LDH lamellar structure, the Co₅Mn-LDH/MWCNT and Ni₅Mn-LDH/MWCNT could generated a current density of 10 mA cm^–2 at overpotentials of ∼300 and ∼350 mV, respectively, in 1 M KOH. In addition, the materials also exhibited outstanding long-term electrocatalytic stability

Enhanced Performance of Photoelectrochemical Water Splitting with ITO@α-Fe₂O₃ Core–Shell Nanowire Array as Photoanode

Hematite (α-Fe₂O₃) is one of the most promising candidates for photoelectrodes in photoelectrochemical water splitting system. However, the low visible light absorption coefficient and short hole diffusion length of pure α-Fe₂O₃ limits the performance of α-Fe₂O₃ photoelectrodes in water splitting. Herein, to overcome these drawbacks, single-crystalline tin-doped indium oxide (ITO) nanowire core and α-Fe₂O₃ nanocrystal shell (ITO@α-Fe₂O₃) electrodes were fabricated by covering the chemical vapor deposited ITO nanowire array with compact thin α-Fe₂O₃ nanocrystal film using chemical bath deposition (CBD) method. The <i>J</i>–<i>V</i> curves and IPCE of ITO@α-Fe₂O₃ core–shell nanowire array electrode showed nearly twice as high performance as those of the α-Fe₂O₃ on planar Pt-coated silicon wafers (Pt/Si) and on planar ITO substrates, which was considered to be attributed to more efficient hole collection and more loading of α-Fe₂O₃ nanocrystals in the core–shell structure than planar structure. Electrochemical impedance spectra (EIS) characterization demonstrated a low interface resistance between α-Fe₂O₃ and ITO nanowire arrays, which benefits from the well contact between the core and shell. The stability test indicated that the prepared ITO@α-Fe₂O₃ core–shell nanowire array electrode was stable under AM1.5 illumination during the test period of 40 000 s