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Efficient charge separation for a photocatalyst can be realized via addition of a co-catalyst, whereby most conventional techniques, i.e., deposition–precipitation, photoreduction, hydrothermal and vapour phase deposition result typically in surface loading effects. Moreover, the loading amount is deliberately kept nominal (below 10 wt%) as excessive loading causes both agglomeration and light blocking issues which limit the performance and stability of the photocatalyst. This work demonstrates one-pot in situ synthesis towards interdispersion and inclusion of a high concentration (Cu : TiO2 weight ratio > 1) of a Cu NP co-catalyst into TiO2 nanosheets without compromising its critical dispersivity and light absorption properties. The exceptional photocatalytic H2 performance of 16.1 ± 0.35 mmol g−1 h−1 stems from the embedment and confinement of the small Cu NPs within the TiO2 matrix which facilitates a shorter diffusion distance, thereby increasing the number of electrons available for catalytic reactions. Thus, this work highlights a facile approach towards optimal interfacing of the hybrid catalyst constituents to mitigate the limited interfacial contact and charge transfer challenges commonly faced in photocatalyst design.

Traditionally, porous carbon can be realized through chemical activation as well as templating with different materials for generation of hierarchical pores. However, the former method often results in the loss of the carbon’s initial structure, while the latter is known to be complex and requires additional procedures to remove the templates. This work demonstrates one-step activation-excavation approach towards simultaneous etching of hierarchical pores with the preservation of its hollow framework for enhanced volatile organic compounds (VOCs) adsorption and supercapacitance performance. The improvement in activity in both applications stems from the micropores, mesopores and hollow interior for containment, selectivity of larger adsorbents and enhanced transport diffusion respectively for VOCs adsorption. Similarly, the hierarchical pore sizes and hollow cavity in supercapacitors serve the purpose of increased electroactive sites, provides shorter diffusion pathway and facilitates ion diffusion for improved capacitive rate. Thus, this facile and effective approach of producing hollow interior and hierarchical pores carbon nanostructures is promising for bifunctional pollutant removal and energy storage solutions.

Two-dimensional (2D) hydrated layered structures have emerged as a fascinating new class of materials for diversified surface mediated redox reactions. Here, a solution-processable 2D hydrated layered structure, Ni(OH)2 nanosheets with hollow TiO2 nanosphere composite has been designed to realize complementary electrochemical and catalysis reactions. The inherent 2D anisotropic lamellar hydrated framework of Ni(OH)2 contains interstitial spaces to promote efficient and reversible insertion/extraction of electrolyte ions without compromising its structural integrity. This translates to a fast switching speed and high stability valence change of metal ions that actively tunes the optical transmittance. Additionally, the Ni(OH)2 nanosheets synergistically play a co-catalyst role to enhance the photocatalytic degradation reactivity of TiO2 nanospheres. Correspondingly, the TiO2 nanospheres are composed of a porous thin shell that provides abundant active sites, distinct cavity diameter with enhanced light harvesting and improved reactant accessibility with a porous framework. Collectively, the nanocomposite is devised to exemplify a monolithically integrated multiple functionalities material system that unprecedentedly delivers photocatalytic degradation coupled electrochromism for environmental and energy conservations.