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Transition metal dichalcogenide (TMD) material-based van der Waals (vdW) heterostructures have gained huge attention due to their superior capabilities and multiple functionalities in electronics and optoelectronic devices. In this work, a gallium telluride/hafnium selenide (GaTe/HfSe2) vdW heterostructure with excellent ohmic contacts is studied. A high gate-modulated rectification ratio (RR) of 6.3 × 105 is attained. Furthermore, the photovoltaic measurement is performed under the illumination of laser light of a wavelength of 532 nm and various powers (20–100 μW). Its rise and decay times (18 μs & 24 μs) are superior among those of various reported vdW heterostructures. The photoresponsivity of GaTe/HfSe2 is enhanced significantly up to with an external quantum efficiency (EQE = 54%) as compared to those of the various reported vdW heterostructures. Such TMD based heterostructure devices would improve the energy harvesting needs along with the multifunctional logic operations. [ABSTRACT FROM AUTHOR]

The rapid recombination of charges of photogenerated electrons and holes severely limits single semiconductor photocatalytic applications. In this study, a simple and facile sol-gel approach was used to synthesize Ba 2- x Ho x Sr 2- y Ni y Fe 12 O 22 ( x = 0, 0.1 and y = 0, 0.5). The composite of holmium-nickel doped barium-strontium ferrite with MXene (Ba 1.9 Ho 0.1 Sr 1.5 Ni 0.5 Fe 12 O 22 @MXene) was synthesized by ultrasonication method. These synthesized samples were subsequently used to photodegrade rhodamine B (RhB) and pendimethalin under visible light illumination. The results of the experiments demonstrated that MXene, as a cocatalyst, considerably reduces the rate of recombination of charges and broadens absorption of visible light by providing increased surface functional groups to improve the photocatalytic activity of synthesized samples. MXene is thermally stable, have high electrical conductivity, have adjustable bandgap, and hydrophilic in nature. The optimized Ba 1.9 Ho 0.1 Sr 1.5 Ni 0.5 Fe 12 O 22 @MXene composite demonstrated an excellent photocatalytic rate by degrading 78.88% RhB and 75.59% pendimethalin in 140 minutes. Moreover, the scavenging experiment revealed that photogenerated electrons and holes were the primary active species involved in RhB and pendimethalin photodegradation, respectively. Ba 1.9 Ho 0.1 Sr 1.5 Ni 0.5 Fe 12 O 22 @MXene showed increased photocatalytic behavior because it has increased surface area which decreases rate of recombination of electron and hole pair, hence photocatalytic activity increases. It is observed that Ba 1.9 Ho 0.1 Sr 1.5 Ni 0.5 Fe 12 O 22 @MXene has potential application in photocatalytic degradation of harmful pollutants., Competing Interests: There are no conflicts of interest to declare for our manuscript being submitted to your journal., (This journal is © The Royal Society of Chemistry.)