Structure–Property Interplay Within Microporous Manganese Dioxide Tunnels For Sustainable Energy Storage

Abstract

Tunnel‐structured manganese dioxides (MnO2), also known as octahedral molecule sieves (OMS), are widely studied in geochemistry, deionization, energy storage and (electro)catalysis. These functionalities originate from their characteristic sub‐nanoscale tunnel framework, which, with a high degree of structural polymorphism and rich surface chemistry, can reversibly absorb and transport various ions. An intensive understanding of their structure–property relationship is prerequisite for functionality optimization, which has been recently approached by implementation of advanced (in situ) characterizations providing significant atomistic sciences. This review will thus timely cover recent advancements related to OMS and their energy storage applications, with a focus on the atomistic insights pioneered by researchers including our group: the origins of structural polymorphism and heterogeneity, the evolution of faceted OMS crystals and its effect on electrocatalysis, the ion transport/storage properties and their implication for processing OMS. These studies represent a clear rational behind recent endeavors investigating the historically applied OMS materials, the summary of which is expected to deepen the scientific understandings and guide material engineering for functionality control.

Sustainable Synthesis of Adipic Acid via MnOx-Catalyzed Electrooxidation of Cyclohexanol in Neutral Electrolyte

“…All MnO x -based composites (MnO x -NR, MnO x /CNT-A1, MnO x /CNT-A2, MnO x /CNT-S, and MnO x /CNT-C) display two distinct phonon modes at 574 cm −1 and 641 cm −1 , characteristic of cryptomelane-type MnO 2 with 2 × 2 tunnel structures. These modes are attributed to the Mn-O stretching vibration and symmetric stretching of MnO 6 octahedra, respectively [ 17 ]. Notably, the well-defined peak at 641 cm −1 confirms the formation of tetragonal α-MnO 2 with high crystallinity.…”

Sustainable Synthesis of Adipic Acid via MnOx-Catalyzed Electrooxidation of Cyclohexanol in Neutral Electrolyte

“…All MnO x -based composites (MnO x -NR, MnO x /CNT-A1, MnO x /CNT-A2, MnO x /CNT-S, and MnO x /CNT-C) display two distinct phonon modes at 574 cm −1 and 641 cm −1 , characteristic of cryptomelane-type MnO 2 with 2 × 2 tunnel structures. These modes are attributed to the Mn-O stretching vibration and symmetric stretching of MnO 6 octahedra, respectively [ 17 ]. Notably, the well-defined peak at 641 cm −1 confirms the formation of tetragonal α-MnO 2 with high crystallinity.…”

Facet-dependent oxysulfidation of Cu 2 O nanomaterials: implications for improving the efficacy of nanopesticides

“…S3a†), 56 and the tiny tunnels between CuS 3 triangles and distorted CuS 4 tetrahedra in the crystal structure are not conducive to mass transport. 57,58 In comparison, covelline consists of an ordered structure of alternating CuS 3 triangles and CuS 4 tetrahedral layers connected by S–S bonds, 59 leaving large spaces between the two CuS 4 –CuS 3 –CuS 4 triple layers (Fig. S3b†).…”

Tailoring Oxidation State of Manganese Enables the Direct Formation of Todorokite

“…44−48 However, considering the successful synthesis of todorokite has only been achieved under hightemperature conditions, the ubiquitous occurrence of todorokite in nature remains elusive. 11,[41][42][43]49 In this study, by utilizing the electrodeposition of Mn 2+ (aq), we demonstrate for the first time the direct formation of todorokite on fluorine-doped tin oxide (FTO) glass within 30 min. We highlight the significant impact of pH and Mg 2+ on the resulting crystalline structure of the electrodeposited Mn oxides.…”

“…The necessity of high temperatures and multiple complex steps for todorokite synthesis in laboratory settings poses challenges to elucidating the natural ubiquity of todorokite. 41,42 Under environmentally relevant conditions, such as room temperature and circumneutral pH, Mn(III/IV) oxide typically forms layered Mn oxide precipitates. 43 Consequently, based on the limited understanding from laboratory systems, the prevailing belief is that natural todorokite likely forms through the transformation of layered Mn oxides rather than direct formation.…”

Sustainable Synthesis of Adipic Acid via MnOx-Catalyzed Electrooxidation of Cyclohexanol in Neutral Electrolyte

“…All MnO x -based composites (MnO x -NR, MnO x /CNT-A1, MnO x /CNT-A2, MnO x /CNT-S, and MnO x /CNT-C) display two distinct phonon modes at 574 cm −1 and 641 cm −1 , characteristic of cryptomelane-type MnO 2 with 2 × 2 tunnel structures. These modes are attributed to the Mn-O stretching vibration and symmetric stretching of MnO 6 octahedra, respectively [ 17 ]. Notably, the well-defined peak at 641 cm −1 confirms the formation of tetragonal α-MnO 2 with high crystallinity.…”

Facet-dependent oxysulfidation of Cu 2 O nanomaterials: implications for improving the efficacy of nanopesticides

“…S3a†), 56 and the tiny tunnels between CuS 3 triangles and distorted CuS 4 tetrahedra in the crystal structure are not conducive to mass transport. 57,58 In comparison, covelline consists of an ordered structure of alternating CuS 3 triangles and CuS 4 tetrahedral layers connected by S–S bonds, 59 leaving large spaces between the two CuS 4 –CuS 3 –CuS 4 triple layers (Fig. S3b†).…”

Tailoring Oxidation State of Manganese Enables the Direct Formation of Todorokite

“…44−48 However, considering the successful synthesis of todorokite has only been achieved under hightemperature conditions, the ubiquitous occurrence of todorokite in nature remains elusive. 11,[41][42][43]49 In this study, by utilizing the electrodeposition of Mn 2+ (aq), we demonstrate for the first time the direct formation of todorokite on fluorine-doped tin oxide (FTO) glass within 30 min. We highlight the significant impact of pH and Mg 2+ on the resulting crystalline structure of the electrodeposited Mn oxides.…”

“…The necessity of high temperatures and multiple complex steps for todorokite synthesis in laboratory settings poses challenges to elucidating the natural ubiquity of todorokite. 41,42 Under environmentally relevant conditions, such as room temperature and circumneutral pH, Mn(III/IV) oxide typically forms layered Mn oxide precipitates. 43 Consequently, based on the limited understanding from laboratory systems, the prevailing belief is that natural todorokite likely forms through the transformation of layered Mn oxides rather than direct formation.…”

Sustainable Synthesis of Adipic Acid via MnOx-Catalyzed Electrooxidation of Cyclohexanol in Neutral Electrolyte

“…All MnO x -based composites (MnO x -NR, MnO x /CNT-A1, MnO x /CNT-A2, MnO x /CNT-S, and MnO x /CNT-C) display two distinct phonon modes at 574 cm −1 and 641 cm −1 , characteristic of cryptomelane-type MnO 2 with 2 × 2 tunnel structures. These modes are attributed to the Mn-O stretching vibration and symmetric stretching of MnO 6 octahedra, respectively [ 17 ]. Notably, the well-defined peak at 641 cm −1 confirms the formation of tetragonal α-MnO 2 with high crystallinity.…”

Facet-dependent oxysulfidation of Cu 2 O nanomaterials: implications for improving the efficacy of nanopesticides

“…S3a†), 56 and the tiny tunnels between CuS 3 triangles and distorted CuS 4 tetrahedra in the crystal structure are not conducive to mass transport. 57,58 In comparison, covelline consists of an ordered structure of alternating CuS 3 triangles and CuS 4 tetrahedral layers connected by S–S bonds, 59 leaving large spaces between the two CuS 4 –CuS 3 –CuS 4 triple layers (Fig. S3b†).…”

Tailoring Oxidation State of Manganese Enables the Direct Formation of Todorokite

“…44−48 However, considering the successful synthesis of todorokite has only been achieved under hightemperature conditions, the ubiquitous occurrence of todorokite in nature remains elusive. 11,[41][42][43]49 In this study, by utilizing the electrodeposition of Mn 2+ (aq), we demonstrate for the first time the direct formation of todorokite on fluorine-doped tin oxide (FTO) glass within 30 min. We highlight the significant impact of pH and Mg 2+ on the resulting crystalline structure of the electrodeposited Mn oxides.…”

“…The necessity of high temperatures and multiple complex steps for todorokite synthesis in laboratory settings poses challenges to elucidating the natural ubiquity of todorokite. 41,42 Under environmentally relevant conditions, such as room temperature and circumneutral pH, Mn(III/IV) oxide typically forms layered Mn oxide precipitates. 43 Consequently, based on the limited understanding from laboratory systems, the prevailing belief is that natural todorokite likely forms through the transformation of layered Mn oxides rather than direct formation.…”