We demonstrate the fabrication of a monolayer graphene/β-Ga 2 O 3 heterostructure and its interesting prospect of producing a suitable Schottky barrier potential for deep-ultraviolet (DUV) responsive photovoltaic device. The transient response behavior shows a faster response time for photovoltaic mode operation of the photodiode. The fast response at a zero bias is due to generation of photocurrent under an internal built-in field in the graphene/Ga 2 O 3 interface without any contribution from the trapped carriers. The fabricated device also shows an excellent photoresponsivity of 6.1 A W À1 with a slower response time at a low reverse bias voltage (À1.5 V). The high photoresponsivity at a bias voltage can be related to carrier multiplication due to carriers trapping/release process. Our findings show that the graphene/β-Ga 2 O 3 heterostructure can be significant for selfpowered/low power consuming DUV detector applications.

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High performance multifunctional electrocatalysts are attracting significant importance for application in energy storage, energy conversion and various other electrochemical reactions. In this prospect, we report on the effective trifunctional electrocatalytic properties of nitrogen (N) doped graphitic carbon nanofibers (CNFs). The CNFs were synthesized on a nichrome (NiCr) foil by chemical vapor deposition (CVD) process. Incorporation of Ni and Cr was observed in the N doped CNFs sample from microscopic and spectroscopic analysis. The metal nanoparticles can be significant in boosting the trifunctional electrocatalytic behavior. The effective oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activities were obtained for the CNFs sample with relatively good overpotential values. The electron transfer number per O2 molecule calculated from Koutecky‐Levich (K‐L) plot was found to be 2e− for the ORR reaction. The OER activity of the CNFs is comparable to commercially available iridium oxide (IrO2), signifying the effectiveness of the developed catalyst. Our study revealed that N doped CNFs with incorporation of metal particles synthesized on a binary metal substrate can be significant as ORR, OER, HER trifunctional electrocatalyst.

Fabrication of heterojunction with transition metal dichalcogenide (TMDC) layers and convention bulk semiconductor is of great interest for optoelectronic device applications. Herein, the influence of interface in a fabricated molybdenum sulfide (MoS2) and p‐type silicon (Si) heterostructure on bias‐dependent photoresponse is demonstrated. The MoS2 layers deposited on the p‐type Si wafer show a photovoltaic action and a photoresponsivity of 139 mA W−1 at 860 nm wavelength for a bias voltage of −5 V. It is observed that the spectral photoresponse of the device enhanced considerably with an applied bias voltage than that of the photovoltaic mode due to an effective field effect across the heterojunction. The increase in photoresponsivity at a higher wavelength (>600 nm) is significant than that of lower wavelength (<500 nm) at the bias voltage. This may due to surface recombination of photocarriers for higher energy photons in the presence of interface states at the MoS2/Si heterojunction. The understanding of photocarriers behavior in the fabricated MoS2/Si heterojunction interface can be critical to develop high photoresponsive heterojunction devices.