However, beyond the initial success of the hematite (α-Fe₂O₃) in water splitting and photocatalysis, this importance is primarily attached to their abundance, chemical stability, and non-toxicity. Nonetheless, their inherent and often dramatic polymorphism and anisotropy can be hampering as well as a guiding factor for their photocatalytic behaviour. Furthermore, the origin of this polymorphism and anisotropy during their laboratory synthesis have hardly been fully understood and controlled. Also, how this mineral-substrate based interfacial structure, of industrial and geochemical importance, is fundamentally related to their electronic structure, band gap, (Eg), light absorption coefficient (α), charge carrier dynamics (e-/h + ), and electron (e-) transfer is also not yet fully understood. The foundational theoretical formulation related to this is constantly evolving. Thus, much remains unknown on such aspects of these oxides. Nonetheless, a few recent studies have shown that the different shapes (shape anisotropy) of the same nanoscale materials can exhibit different catalytic efficiency but lack an appropriate justification and theoretical support. Also, they often lack a deep understanding of light-matter interaction and interfacial charge dynamics. In the case of iron as a mineral, the understanding of the origin and evolution of shape anisotropy and its relation to photocatalytic behaviour can inform both the geochemical processes and sustainable photocatalyst design. Interestingly, we reported a similar anisotropy-dependent photocatalytic behaviour in our previous study of zinc and germanium oxide nanoparticles. Moreover, beyond the claims of Kleber et al. (2021) toward the role of nano-scale mineralorganic interfaces in nature, our findings indicate that an efficient industrial catalyst design must include an aspect of shape anisotropy. However, finding a sustainable as well as efficient laboratory methods for shape and surface-controlled synthesis is still a challenge. A few reports on nature-inspired biomimetic approaches for inorganic chemicals could be encouraging-as nature has long been known to produce chemicals with ultimate control and precision. However, the understanding of the relevant natural processes controlling the shape and size of inorganic oxides appears inadequate, let alone the simulation of the natural (biological or environmental) conditions in the laboratory. Nevertheless, the simpler natural processes like mineralisation in geological and soil environments have also been discussed off and on for such control. Interestingly, some recent reports on mineralisation and crystallisation in the natural environment have discussed natural crystallisation in a synthetic context. It has been said that crystallisation in the natural environment is assisted by organic ligands present in soil and geological environments. This leads to precisely controlled shape and size of nanocrystals, which bear similarities to the enzymes and acid-controlled biomimetic approaches used in a laboratory setup. It has also been highlighted that such crystallisation generally proceeds through the non-classical crystallisation pathway. Nonetheless, much research effort has to be put in this direction. This work investigates the origin and evolution of shape anisotropy in iron oxide nanocrystals using biogenic (lignocellulosic) agro-industrial waste (PM) as well as fine chemical-based ligands in aqueous sol-gel process under the framework of non-classical crystallisation theory (NCCT). Also, beyond the traditionally known interface and material-centric approach, we utilize a less common approach to explain and understand the observed differences in photocatalytic behaviour of the nano-sized iron oxide-based photocatalysts with different sizes and shapes. Thus, this work offers a fresh insight into biogenic ligand-based anisotropic control over mineral oxides and a mechanistic understanding of structure-activity-correlation using the concept of the potential of zero charge (EPZC), electrochemical work function (𝛷 𝑎𝑑 0 ), and electrochemically active surfaceactive area (ESCA).