Over the past few years, many approaches have been developed progressively to produce hydrogen (H2) from water under solar light irradiation. This process of fuel production is clean, potentially cost-effective,...

Photocatalytic water splitting is considered one of the most important and appealing approaches for the production of green H2 to address the global energy demand. The utmost possible form of artificial photosynthesis is a two‐step photoexcitation known as “Z‐scheme”, which mimics the natural photosystem. This process solely relies on the effective coupling and suitable band positions of semiconductors (SCs) and redox mediators for the purpose to catalyze the surface chemical reactions and significantly deter the backward reaction. In recent years, the Z‐scheme strategies and their key role have been studied progressively through experimental approaches. In addition, theoretical studies based on density functional theory have provided detailed insight into the mechanistic aspects of some breathtakingly complex problems associated with hydrogen evolution reaction and oxygen evolution reaction. In this context, this critical review gives an overview of the fundamentals of Z‐scheme photocatalysis, including both theoretical and experimental advancements in the field of photocatalytic water splitting, and suggests future perspectives.

In the present study, green silver nanoparticles (Ag 2 ONPs) were prepared from aqueous and ethanolic leaves extract of Rhamnus virgata in a facile, green, cost-effective, and eco-friendly way. The color changes from light brown to brownish black determined the synthesis of Ag 2 ONPs (Aq) and Ag 2 ONPs (Et). The phytofabrication of Ag 2 ONPs was confirmed using various spectroscopic and microscopic techniques: energy-dispersive X-ray spectroscopy, dynamic light scattering, ultraviolet-visible spectroscopy, Fouriertransform infrared, X-ray powder diffraction, Raman, scanning electron microscopy, and transmission electron microscopy. Detailed in vitro biological activities determined significant biopotentials for Ag 2 ONPs. The Ag 2 ONPs (Aq) and Ag 2 ONPs (Et) were investigated for anticancer potential against HUH-7 (IC 50 : 9.075 μg/ml for Ag 2 O (Aq) and 25.66 μg/ml for Ag 2 O (Et)) and HepG2 (IC 50 : 25.18 μg/ml for Ag 2 O (Aq) and IC 50 : 27.74 μg/ml for Ag 2 O (Aq)) cell lines. Concentration-dependent cytotoxicity was performed against brineshrimps (IC 50 : 36.04 μg/ml for Ag 2 O (Aq) and 28.82 μg/ml for Ag 2 O (Et)) and Leishmanial parasite (amastigotes and promastigotes). Disc-diffusion method revealed significant antimicrobial activities. In addition, significant enzyme inhibitory activity and antiradical potentials were studied. The hemocompatible nature of Ag 2 ONPs (Aq) and Ag 2 ONPs (Et) was revealed using biocompatibility tests. In conclusion, the green Ag 2 ONPs (Aq) and Ag 2 ONPs (Et) are nontoxic and biocompatible and has shown significant biological activities. We further encourage in vivo studies to ensure biosafety and biocompatibility, so that they can be effectively utilized in nano-pharmaceutical industries.