Figures (9)  Tables (2)

    • Figure 1. 

      Lignocellulose framework in plant cell walls[13].

    • Figure 2. 

      Overview of biomass conversion technologies[22].

    • Figure 3. 

      Piezocatalysis milestones from 2010 to 2025, covering materials, mechanisms, and applications[23].

    • Figure 4. 

      Polarization-induced charge behavior in ferroelectric, pyroelectric, and piezoelectric materials below Tc[26].

    • Figure 5. 

      Crystal structures and phase configurations of representative piezoelectric materials: (a) wurtzite CdS, (b) Ti3C2Tx MXene, (c) cubic and tetragonal BaTiO3, (d) wurtzite ZnO, (e) α-, β-, and γ-phases of PVDF, and (f) orthorhombic KNbO3 [44,46−50].

    • Figure 6. 

      Illustration of energy band and screening charge effect mechanisms in piezocatalysis[27].

    • Figure 7. 

      Schematic illustration of the piezocatalytic energy band mechanism involving O2 reduction and H2O oxidation, showing the roles of ECB, EVB, Eg, and piezopotential (φP)[20].

    • Figure 8. 

      Illustration of the screening charge effect in piezocatalysis: (a) initial electrostatic balance of polarized material; (b) release of screening charges forming ROS under compression; (c) rebalanced state after charge minimization; (d) charge adsorption from electrolyte upon strain release[20].

    • Figure 9. 

      Schematic illustration of the: (a) energy band and screening charge mechanisms in piezocatalytic biomass conversion; (b) mechanism of five catalytic technologies (photocatalysis, piezocatalysis, electrocatalysis, pyrocatalysis, and tribocatalysis)[20].

    • Sr No. Material Crystal structure Key features Key piezoelectric parameters Relevance to biomass conversion
      1 BaTiO3 Perovskite (ABO3) High Tc = 120 °C, spontaneous polarization d33: 190–300 pC/N;
      Tc: 120 °C      		 Strong piezoelectric polarization enhances ROS generation, promoting oxidative degradation of biomass polymers
      2 Pb(Zr1−xTix)O3 (PZT) Perovskite (ABO3) Tunable piezoelectric properties, high electromechanical coupling coefficient d33: 300–600 pC/
      N; kp ≈ 0.6–0.7      		 Efficient electron–hole separation drives selective oxidation and depolymerization of biomass compounds
      3 KNbO3 Perovskite (ABO3) Lead-free, high piezoelectric response d33: 80–160 pC/N Facilitates ROS-mediated biomass conversion while avoiding toxic lead content
      4 (Na1−xKx)NbO3 (NKN) Perovskite (ABO3) High mechanical strength, lead-free d33: 100–250 pC/N Facilitates ROS-mediated biomass conversion while avoiding toxic lead content
      5 AgNbO3 Perovskite (ABO3) High piezoelectric activity, lead-free d33: 50–100 pC/N Promotes generation of ·OH and ·O2− radicals for biomass depolymerization
      6 BiFeO3 Perovskite (ABO3) Multiferroic properties, high polarization Ps: 50–90 μC/cm² Combines piezoelectric and ferroelectric properties to efficiently degrade biomass molecules
      7 ZnO Wurtzite (hexagonal) High surface area, UV-active, piezoelectric d33: 10–12 pC/N;
      BG: 3.2 eV      		 Generates ROS under mechanical stimulation; high surface area facilitates biomass adsorption and oxidation
      8 GaN Wurtzite (hexagonal) High thermal stability, piezoelectric d33: 3–5 pC/N Mechanically induced polarization produces ROS for biomass depolymerization under stress
      9 CdS Wurtzite (hexagonal) Visible light absorption, piezoelectric BG: 2.4 eV;
      d33: 5–10 pC/N      		 Mechanically induced polarization produces ROS for biomass depolymerization under stress
      10 CdSe Wurtzite (hexagonal) Narrow bandgap, piezoelectric BG: 1.7 eV Generates ROS efficiently for oxidative cleavage of biomass molecules
      11 Ti3C2Tx 2D (hexagonal) High conductivity, hydrophilic surface, tunable surface chemistry Conductivity:
      103–104 S/m      		 Generates ROS efficiently for oxidative cleavage of biomass molecules
      12 PVDF Polymer (ferroelectric) Flexible, high piezoelectric response
      in β-phase      		 d33: 20–30 pC/N Mechanically flexible ROS generation, enabling biomass depolymerization in dynamic setups
      13 PVDF-TrFE Polymer (ferroelectric) Enhanced piezoelectric properties, flexible d33: 30–40 pC/N Mechanically flexible ROS generation, enabling biomass depolymerization in dynamic setups
      14 Bi0.5Na0.5TiO3 Perovskite (ABO3) Lead-free, high piezoelectric response d33: 60–120 pC/N Efficiently generates ROS for selective oxidative depolymerization of biomass
      15 SrTiO3 Perovskite (ABO3) High dielectric constant, piezoelectric Relative permittivity
      (εr): 300      		 Enhances electron–hole separation, producing ROS for biomass oxidation
      16 Bi4Ti3O12 Layered Perovskite High polarization, photocatalytic activity Ps: 50 μC/cm² Combines piezoelectric and photocatalytic effects to degrade biomass molecules efficiently
      17 Bi4NbO8X
      (X = Cl, Br)      		 Layered Perovskite High polarization, photocatalytic activity BG: 2.5–3.0 eV Promotes ROS generation under mechanical stress for biomass depolymerization
      18 Bi0.5Na0.5TiO3-BaTiO3 Perovskite (ABO3) Solid solution, high piezoelectric response, lead-free d33: 150–250 pC/N Synergistic properties of BNT and BaTiO3 enhance ROS production, facilitating efficient biomass conversion
      Bi0.5Na0.5TiO3: bismuth sodium titanate (BNT), SrTiO3: strontium titanate, Bi4Ti3O12: bismuth titanate, Bi4NbO8X: bismuth niobium oxyhalides, Bi0.5Na0.5TiO3-BaTiO3: bismuth sodium titanate–barium titanate (BNT-BT); BG: bandgap.

      Table 1. 

      Piezoelectric materials used in piezocatalysis and their significance for biomass conversion[7,10,24−32]

    • Sr. No. Authors Year Study Research aim Materials used Conditions Methodology Performance metrics Key findings Areas of application Ref.
      1 El-Fawal et al. 2025 Biomass conversion and engineered biochar To evaluate the catalytic role of engineered biochar in biomass conversion Biomass residues; engineered biochar Pyrolysis routes Review — Highlights biochar as catalytic support relevant to piezo-catalysts Biomass-derived catalyst supports [19]
      2 Xin et al. 2025 MXene–Co PMS activator To activate PMS for oxidation of organic biomass-like matter Ti3C2MXene-Co Aqueous oxidation PMS activation tests ~90% degradation efficiency Strong oxidation relevant to biomass depolymerization Biowaste oxidation [41]
      3 Feng et al. 2022 Piezocatalytic sludge dewatering To evaluate piezoelectric BaTiO3 for EPS disruption in biomass (sludge) BaTiO3; sewage sludge Pressure
      0.3–0.6 MPa      		 EPS oxidation, EPR Moisture: 96.7% → 63.9% Moisture reduced from 96.7% to 63.9%; strong piezo-oxidation Biomass waste management [61]
      4 Liao et al. 2022 Cu3B2O6 piezocatalysis To study polarization-induced ROS for organic oxidation Cu3B2O6 Ultrasonic vibration Piezocatalytic degradation ~85%–95% removal Breaks C–C and C–H bonds similar to biomass depolymerization Biomass-like organic breakdown [69]
      5 Fu et al. 2022 BaTiO3@TiO2 nanofibers To enhance dipole alignment for stronger piezo-activity BaTiO3@ TiO2 nanofibers Ultrasonic + light Piezophotocatalysis ~95% degradation High degradation of aromatic organics (biomass analogues) Aromatic biomass compound oxidation [90]
      6 Phuong et al. 2022 Lead-free piezocatalytic CO2 reduction CO2 → fuels via piezoelectric particulates Lead-free ferroelectrics Ultrasonication CO2 reduction CO yield improvement (~2–3 times) Efficient carbon conversion relevant to biomass–CO2 cycles Bioenergy and carbon cycling [81]
      7 Tian et al. 2021 Piezocatalytic BPA degradation To oxidize BPA (lignin-like aromatic) SnS2/CNF membrane Ultrasonication Piezocatalytic oxidation ~90% removal High removal of BPA, similar to lignin monomer oxidation Biomass-derived phenolic depolymerization [53]
      8 Shi et al. 2021 Piezocatalytic foam for organic degradation To create foam-based piezocatalytic oxidation system Piezo-active foam Ultrasonic vibration Organic degradation ~80–90% removal Efficient degradation of complex high-MW organics Biowaste treatment [54]
      9 Meng et al. 2020 Fe@MoS2 piezocatalyst To degrade complex antibiotic molecules resembling biomass organics Fe@MoS2 Mechanical vibration Piezocatalysis ~85% degradation Strong oxidation of complex organic molecules Organic biowaste [67]
      10 Liu et al. 2020 BaTiO3 morphology for dye degradation To investigate morphology–activity relationships BaTiO3 nanostructures Ultrasonication Kinetics and degradation tests ~90% dye removal Efficient breakdown of dyes (biomass aromatic analogs) Biomass-related aromatic conversion [65]
      11 Wei et al. 2019 Au/BiVO4 bifunctional piezocatalysis To degrade chlorophenols (lignin-derived) Au/BiVO4 Ultrasonication Piezocatalysis ~92% removal High degradation of chlorophenols resembling lignin fragments Lignin model molecule conversion [55]
      12 Lan et al. 2019 BaTiO3/Ag3PO4 piezophotocatalysis To degrade N-heterocyclic organics BaTiO3/Ag3PO4 Light + vibration Piezophotocatalysis ~93% degradation Efficient breakdown of heterocyclic organics Biowaste and agrochemical residues [92]
      13 Sankaran et al. 2021 Nanotechnology in lignocellulose conversion To apply nanomaterials for biomass breakdown Nanostructures; biomass Various Review — Demonstrates nanomaterial efficacy in depolymerizing biomass Lignocellulosic biomass valorization [13]
      14 Sudrajat et al. 2023 Review on piezoelectric photocatalysis To summarize mechanism, materials, and applications ZnO, BaTiO3, BiFeO3, MoS2 composites Light + mechanical stress (ultrasound/
      vibration)      		 Review — Piezoelectric field improves charge separation and boosts performance Water treatment, pollution control, hydrogen production [26]
      15 Demirbas et al. 2009 Biomass-derived activated carbon To evaluate agricultural biomass conversion into catalysts Agricultural biomass Pyrolysis Review — Biomass-derived carbon widely used as catalytic support Biochar-supported piezo-catalysts [62]
      16 Ren et al. 2025 Defect-engineered piezocatalysis To enhance piezocatalytic activity via defect engineering (K,Na)NbO3 (KNN) Ultrasonic vibration Piezocatalytic degradation Rate constant increased by 1.3–4.4× vs pristine Oxygen vacancies significantly enhance charge separation and ROS generation Organic pollutant degradation (biomass analogues) [93]
      17 Zhao et al. 2025 Al-doped BCZT piezocatalyst To improve degradation efficiency via doping Al3+-doped BCZT Ultrasonication Piezocatalytic degradation 84.2% degradation in
      70 min      		 Defect engineering improves catalytic efficiency compared to undoped materials Organic pollutant degradation [94]
      18 Park et al. 2025 PVDF-based piezocatalysis To evaluate energy-efficient degradation system PVDF/AC-NaCl composite Fluid flow/mechanical stimulation Piezocatalytic degradation 99.53% degradation efficiency Lower energy consumption compared to conventional AOPs Water treatment/
      biomass-like organics      		 [95]
      19 Ran et al. 2024 Defect-mediated piezocatalysis To enhance ROS generation via dynamic defects Defect-engineered catalyst Mechanical vibration H2O2-assisted piezocatalysis Enhanced in-situ H2O2 generation Dynamic defects improve catalytic activity and reaction pathways Environmental remediation/
      biomass analogues      		 [96]
      20 Lu et al. 2024 Borate-based piezocatalysis To evaluate pharmaceutical degradation efficiency CaZn2(BO3)2 Ultrasonication Piezocatalytic degradation 100% (ibuprofen), 83.8% (CBZ) in
      36 min      		 High degradation efficiency with fast kinetics compared to conventional systems Pharmaceutical/
      biomass-derived pollutants      		 [97]

      Table 2. 

      Case studies demonstrating the application of piezocatalysis in biomass conversion