Tailoring Active Sites in Mesoporous Defect‐Rich NC/V_o‐WON Heterostructure Array for Superior Electrocatalytic Hydrogen Evolution

Abstract

Tailoring active sites in earth‐abundant non‐noble metal electrocatalysts are required toward widespread applications in sustainable energy fields. Herein, an integrated mesoporous heterostructure array is reported by a hydrogenation/nitridation‐induced in situ growth strategy. Highly conductive oxygen‐vacancies‐rich tungsten oxynitride (Vo‐WON) nanorod array acts as the backbone encapsulated by ultrathin nitrogen‐doped carbon (NC) nanolayers, forming high‐quality shell/core NC/Vo‐WON heterostructures. Density functional theory calculations reveal that defect‐rich heterostructure arrays not only enhance the conductivity and modulate electronic structure but also promote the adsorption and dissociation of reactants and offer substantial potential sites. As expected, porous NC/Vo‐WON array exhibits a small overpotential of 16 mV at the current density of 10 mA cm−2 and a low Tafel slope of 33 mV per decade in alkaline media, accompanied by negligible loss upon a large current density over 100 h. Benefiting from outstanding electrocatalytic hydrogen evolution reaction performance and stability, this defective heterostructure could serve as a prominent alternative electrocatalyst for renewable energy applications.

Scalable Synthesis of One‐Dimensional Mesoporous ZnMnO3 Nanorods with Ultra‐Stable and High Rate Capability for Efficient Lithium Storage

“…Apparently,a ll the XRD reflections in Figure 2a can be perfectly indexedi nto the cubic ZMO (JCPDS no. 19-1461), [9,10,18] and no other diffraction signals for impurities, indicative of the high phase purity of the resultantZMO-NRs. The corresponding thermogravimetric analysis (TGA) of the oxalate precursor in air,a si llustrated in Fig…”

“…The specific pre-lithiated method is the same as our another work. [10] The commercial Li-Ni 0.8 Co 0.1 Mn 0.1 O 2 (LNCM) electrode was used as the cathode, which was fabricated by casting am ixed slurry of LNCM (80 wt %), carbon black (10 wt %), and polyvinylidene fluoride (10 wt %) on Al foil. The corresponding mass ratio of cathode/anode was evaluated to be approximately 2.9.…”

“…The Zn 2p spectrumc an be fitted to Zn 2p 1/2 and Zn 2p 3/2 peaks centered at 1044.1 and 1021.0 eV,r espectively, implyingt he existence of bivalent Zn in the ZMO-NRs (Figure 3b). [10,19] As for the Mn 2p region, the Mn 2p 3/2 spectra can be divided into three peaks, where the two major peaks at (Figure 3c). [6,10,20] Additionally,t he O1ss pectrum demonstrates two fitting peaks at 531.1 and 529.8 eV (Figure 3d), which should be ascribed to the absorbed oxygen/H 2 Oa nd/or oxygen-metal (Zn/Mn) coordination.…”

“…[10,19] As for the Mn 2p region, the Mn 2p 3/2 spectra can be divided into three peaks, where the two major peaks at (Figure 3c). [6,10,20] Additionally,t he O1ss pectrum demonstrates two fitting peaks at 531.1 and 529.8 eV (Figure 3d), which should be ascribed to the absorbed oxygen/H 2 Oa nd/or oxygen-metal (Zn/Mn) coordination. [7] The microstructure and morphology of the as-fabricated ZMO-NRs were characterized by using field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM).…”

“…[8,9] Nevertheless,t he ZnMnO 3 electrode still intrinsically suffers from poor lithiums toragep roperties owing to itsl arge volumee xpansion, sluggish electrolyte diffusion, and poor reactionk inetics of lithiumi nsertion/extraction, which severely limits its practical application.T os olve these critical issues, numerous endeavors have been made to alter the structurald esign (i.e.,d imension, morphology,a nd porosity) of the ZnMnO 3 electrodes to enables atisfactory cycling and rate performance. [10][11][12] Among the variousr eported structures,1 Dn ano-architectures like nanorods (NRs), nanowires,a nd nanotubes (NTs ), especially those with inner mesopores,h ave been considered as an ideal choice owing to their short ionic/electronic transport pathsa nd large active contacting sites for lithium storage. [13][14][15] In particular, these unique pores can also act as a" structural buffer" to mitigate the structural damagef rom the large volumee xpansion of metal oxides.…”