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[Display omitted] • Fundamentals of phosphorene (PN) and graphdiyne (GDY) are briefly discussed. • Structure, fabrication routes and modification strategies. • Advances in PN and GDY based heterostructures for photocatalytic hydrogen evolution. • Environment stability, challenges and future perspectives. Hydrogen evolution from water splitting using semiconductor photocatalysis is regarded as a sustainable and clean energy solution. Among various new age materials, the two-dimensional (2D) monoelemental materials as graphdiyne (GDY) and phosphorene (PN) showing excellent performance owing to their 2D atomic structure and unique properties, have drawn considerable attention. Graphdiyne (GDY) is a two-dimensional carbon-based compound having sp and sp2 hybridized carbon, diacetylene linkage, triangular holes framework and customizable band gap. Different stacking arrangements and homogenous pores in GDY can produce electronic characteristics, opening the door to intriguing energy applications. On the other hand, phosphorene derived from black phosphorous (BP) exhibits strong hole mobility, a variable band gap and broad optical absorption spectrum. With a significant increase in photo-excited charge-separation efficacy, the development of heterostructured photocatalysts driven by BP/PN and GDY has recently become the subject of study in photocatalysis. The recent advancements in development of phosphorene and graphdiyne and their accompanying heterostructured photocatalysts is outlined here, along with their structure, characteristics, synthetic routes and photocatalytic applications. In addition, the photocatalytic applications of PN and GDY based composites and heterostructures have been reviewed and summarised for photocatalytic hydrogen evolution through water splitting. Environmental stability of these heterostructured photocatalysts and the difficulties they pose have been thoroughly investigated for their more effective and extensive uses in the future. [ABSTRACT FROM AUTHOR]

The dramatic rise in carbon dioxide levels in the atmosphere caused by the continuous use of carbon fuels continues to have a significant impact on environmental degradation and the disappearance of energy reserves. Past few years have seen a significant increase in the interest in photocatalytic carbon dioxide reduction because of its ability to lower CO 2 releases from the burning of fossil fuels while also producing fuels and important chemical products. Because of their excellent catalytic efficiency, great uniformity, lengthy charge diffusion layers and texture flexibility that enable accurate band gap and band line optimization, perovskite-based nanomaterials are perhaps the most advantageous among the numerous semiconductors proficient in accelerating CO 2 conversion under visible light. Firstly, a brief insight into photocatalytic CO 2 conversion mechanism and structural features of perovskites are discussed. Further the classification and selection of perovskites for Z and S-scheme heterojunctions and their role in photocatalytic CO 2 reduction analysed. The efficient modification and engineering of heterojunctions via co-catalyst loading, morphology control and vacancy introduction have been comprehensively reviewed. Third, the state-of-the-art achievements of perovskite-based Z-scheme and S-scheme heterojunctions are systematically summarized and discussed. Finally, the challenges, bottlenecks and future perspectives are discussed to provide a pathway for applying perovskite-based heterojunctions for solar-to-chemical energy conversion. [Display omitted] • Insight into the mechanism and research progress of photocatalytic CO 2 reduction. • Properties of perovskites as photocatalysts and their synthetic routes. • Boosting the CO 2 conversion through perovskite based Z and S-scheme heterojunctions • The charge transfer mechanism and designing of perovskite based heterojunctions • The future expectations, challenges and outlook are presented. [ABSTRACT FROM AUTHOR]

Here in, we report a, wide spectrum active, Bi nanodots incorporated CuBi 2 O 4 /Bi/CuFe 2 O 4 (CBC) heterojunction for synchronous photodegradation of imidacloprid pesticide (ICP) and photo-reduction of Cr(VI) to Cr(III). The best performing heterojunction sample CBC-30 shows nearly 100% Cr(VI) photo reduction (in less than 45 min) along with 98.2% ICP removal in 60 min. 88.7% Cr (VI) reduction & 83.2% ICP degradation was achieved under sunlight with good activity in NIR region. Scavenging experiments reveal the synchronous role of photoreduction-oxidation with electrons as active species for chromium reduction and holes for organic pollutant degradation. This is ensured by effective Z-scheme transfer between CuBi 2 O 4 and CuFe 2 O 4 leading to protection of high potential conduction and valence bands with strong redox capabilities. The Bi nanodots played an important role via wide spectral response owing its surface plasmon resonance as well as photoinduced electron transfer mediation which promotes the electrons transfer efficiency and enhanced photocatalytic ability. [Display omitted] • Z-scheme CuBi 2 O 4 /Bi/CuFe 2 O 4 has excellent charges separation efficiency. • Bi nanodots-wide spectral activity-mediator- provide hot electrons. • Remarkable synchronous removal of imidacloprid and Cr (VI). • Degradation route for ICP and cooperative mechanism for reduction-degradation. • Efficient activity in solar light and river water too. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni 5 P 4 /g-C 3 N 4 S-scheme dual-function heterojunction photocatalyst was prepared. • 25NP/CN junction shows 40.1 mmol g-1h-1H 2 evolution and 94.4 % CBZ removal in a coupled process. • Holes and OH radicals for CBZ degradation and electrons for H 2 generation via e-/H 2 O and 2e-/2H+. • Intermolecular H+ transfer via cyclic intermediate between Ni and degradation products. • Junction works in oxic/anoxic mediums- detailed mechanisms analysed. With a goal of waste-to-energy conversion, herein we report synchronous hydrogen evolution and pollutant degradation via photocatalysis utilizing novel Ni 5 P 4 /g-C 3 N 4 S-scheme (Step scheme) heterojunction. The 25 %Ni 5 P 4 /g-C 3 N 4 (25NP/CN) sample generates 40.1 mmol g-1h-1hydrogen evolution and 94.4 % carbamazepine degradation simultaneously under visible light and anaerobic conditions. Furthermore, the hydrogen evolution with carbamazepine, bisphenol A, sulfamethoxazole and rhodamine B is manifolds higher than in water. From The in-situ XPS results confirm the S-scheme transfer between Ni 5 P 4 and g-C 3 N 4. The presence of Ni0@Ni 5 P 4 where strong covalent interactions between Ni0 and Ni-P single layers on Ni 5 -P 4 not only enhanced the visible absorption, charge transfer but also leads to hydrogen formation by H+ transfer via a cyclic intermediate in a co-ordinate complex of degradation intermediates with Ni. This route is in addition to obvious e-/H+. The CBZ degradation and hydrogen evolution in aerobic/oxic conditions was also studied and 25NP/CN performs well under this atmosphere, inferring that oxidised intermediates act as electron donors and maintains the H 2 evolution in longer run too. The photogenerated holes directly oxidized the pollutant in addition to OH radicals in anoxic medium and separated/accumulated electrons leads to hydrogen evolution. The scavenging experiments reveal that photogenerated holes directly oxidized the pollutant in addition to OH radicals in anoxic medium and separated/accumulated high potential electrons (via S-scheme transfer) leads to hydrogen evolution. The clean energy production and pollutant mineralization are synchronously achieved. Henceforth, a waste-to-energy route is proposed by coupling photocatalytic hydrogen evolution to environmental restoration. [ABSTRACT FROM AUTHOR]

• Novel 3-D silicate glass@Cu 2 O/Cu 2 V 2 O 7 p-n heterojunction fabricated. • Internal electric field-deep contact-facilitation of charge carrier movement. • High performance removal of sulfamethoxazole under visible light. • O 2 − as active species-ESR probe-high potential band protection-Z-scheme. • 3-D silicate glass-transmission & light scattering-high quantum yield. Focusing on the treatment of pharmaceuticals contaminated water by advanced oxidation processes, a novel three dimensional silicate glass matrix (3-DG) coupled Cu 2 O/Cu 2 V 2 O 7 p-n heterojunction was constructed by in-situ hydrothermal technique. The optimal Cu 2 O/Cu 2 V 2 O 7 with 30 wt % Cu 2 V 2 O 7 (CV-30) degrades 90.1 % sulfamethoxazole (SMX) in 60 min and nearly 100 % removal in 45 min via coupling with 3-DG. Under natural sunlight ∼ 80 % SMX removal was observed. The internal electric field of the p-n junction facilitates the electron flow via the interface. 3-D silicate glass increases the visible light absorption dramatically via internal reflection which facilitates higher exposure for the junction and shortens the diffusion length of charge carriers. The effect of reaction parameters suggests that HCO 3 − and C O 3 2 − ions substantially escalate the SMX removal rate. Scavenging experiments and ESR probe suggest O 2 − as the main active species followed by OH radicals. The degradation products were detected by LC–MS analysis and a degradation mechanism was also predicted. The photocatalytic mechanism was explained in terms of the electron transfer facilitated by conventional transfer and Z-scheme. This strategy to construct such highly visible and solar active p-n heterojunctions will pave way for future opportunities for the degradation of recalcitrant pharmaceutical pollutants. [ABSTRACT FROM AUTHOR]