Facile Designed Manganese Oxide/Biochar for Efficient Salinity Gradient Energy Recovery in Concentration Flow Cells and Influences of Mono/Multivalent Ions

Abstract

Development of effective, environmentally friendly, facile large-scale processing, and low-cost materials is critical for renewable energy production. Here, MnO x /biochar composites were synthesized by a simple pyrolysis method and showed high performance for salinity gradient (SG) energy harvest in concentration flow cells (CFCs). The peak power density of CFCs with MnO x /biochar electrodes was up to 5.67 W m –2 (ave. = 0.91 W m –2 ) and stabilized for 500 cycles when using 1 and 30 g L –1 NaCl, which was attributed to their high specific capacitances and low electrode resistances. This power output was higher than all other reported MnO 2 electrodes for SG energy harvest due to the synergistic effects between MnO x and biochar. When using a mixture with a molar fraction of 90% NaCl and 10% KCl (or Na 2 SO 4 , MgCl 2 , MgSO 4 , and CaCl 2 ) in both feed solutions, the peak power density decreased by 2.3–40.1% compared to 100% NaCl solution with Ca 2+ and Mg 2+ showing the most pronounced negative effects. Our results demonstrated that the facile designed MnO x /biochar composite can be used for efficient SG energy recovery in CFCs with good stability, low cost, and less environmental impacts. When using natural waters as the feed solutions, pretreatment would be needed.

Boosted brackish water desalination and water softening by facilely designed MnO2/hierarchical porous carbon as capacitive deionization electrode

“…1 c). More importantly, the feature at 1103 cm −1 demonstrates the presence of the conducting form of PANI on the surface of HPC, and the feature at approximately 511 cm −1 proves the existence of Mn-O on the MnO 2 /HPC composite surface ( Evans et al., 2019 ; Tan et al., 2021 ). The transmission electron microscopy (TEM) images of the MnO 2 /HPC and PANI/HPC clearly show that both MnO 2 and PANI were formed on the HPC surface, respectively ( Fig.…”

Reduced Lattice Constant in Al‐Doped LiMn2O4 Nanoparticles for Boosted Electrochemical Lithium Extraction

“…The high‐frequency semicircle represents the charge transfer resistance ( R ct ), and the low‐frequency region describes the ionic diffusion resistance ( σ ). [ 43 ] Compared to the LMO electrode ( R ct = 0.63 Ω, σ = 4.12 Ω), the LMO‐Al0.05 electrode ( R ct = 0.42 Ω, σ = 2.99 Ω) had a relative lower electrode resistance, implying that Al doping may facilitate Li + diffusion (Figures 2d and S3, Supporting Information). Previous studies have demonstrated that Al doping can enhance material conductivity and improve Li + diffusion behavior in LMO electrode.…”

Unraveling Flow Effect on Capacitive Energy Extraction from Salinity Gradients

“…6 Beyond its substantial potential, salinity gradient energy also holds a theoretical advantage in terms of relatively high volumetric power density. 7,8 Capacitive mixing (CapMix) represents one of the popular technologies to harvest blue energy. 9 The CapMix method is based on capacitive double-layer expansion (CDLE), which involves two electrodes submerged alternatively in the stream of seawater (SW) or freshwater (FW), forming a capacitor.…”

“…Salinity gradient energy, generated by mixing two solutions of different salt concentrations, is regarded as a promising source of renewable energy, , which can boost an estimated global power potential ranging from 1.40 to 2.60 terawatt . Beyond its substantial potential, salinity gradient energy also holds a theoretical advantage in terms of relatively high volumetric power density. , …”