Ultrastable, High Photoelectrocatalytic Performance of Altervalent Cation-Doped BiVO₄ Photoanode and Effect of Interfacial Contact with Nanoporous Carbon for Seawater Splitting Using a 3D-Printed Flow Device

Solar-driven direct seawater electrocatalysis is a promising technology for sustainable large-scale green-H2 fuel generation. In this work, we systematically investigate the influence of altervalent cation doping into the Bi3+ and V5+ sites of scheelite BiVO4 via a sustainable microwave-assisted hydrothermal (MW-HT) technique within a few minutes (12 min) at as low a temperature of 190 °C. We observed that lower-valent cation (Cs+, Ba2+, Co2+, and In3+) doping favors monoclinic-phase formation; however, higher-valent cations (Hf4+, Nb5+, and Mo6+) facilitated the thermodynamically unfavorable tetragonal-zircon type BiVO4. Interestingly, mixed phases of monoclinic-tetragonal BiVO4 have been obtained upon codoping of Co and Mo, exhibiting enhanced photocurrent density (Jp = 5.8 mA cm–2) among other doped BiVO4 samples. To increase the overall charge-transfer kinetics, we construct a nanoporous carbon with a Co and Mo codoped BiVO4 hybrid photoanode showing a remarkable (∼5-fold) enhancement in photoelectrochemical (PEC) freshwater splitting with the highest recorded photocurrent density of Jp = 6.9 mA cm–2 at 1.23 V vs RHE, AM1.5 G in 0.5 M Na2SO4 electrolyte solution, in comparison to pristine BiVO4 (1.45 mA cm–2) under simulated visible light. The superior performance is due to oxygen vacancy (OV)-related defect levels functioning as electron-trap sites promoting fast charge separation and surface adsorption for generating excess holes at the nanohybrid photoanode. In order to investigate how the nanohybrid photoanode affects the charge-carrier recombination rate and oxygen evolution reaction (OER) in seawater, we designed a compartmentalized three-dimensional (3D)-printed membrane-less, continuous-flow PEC device to produce massive H2 fuel. Significantly, we observed an enhanced Jp of 3.8 mA cm–2 accompanied by an outstanding long-term photostability of 4 h, achieved due to the rapid transfer of photostimulated holes from the nanohybrid photoanode to the electrolyte, promoted by the internal electric field over the constructed Mott–Schottky heterostructure. Thus, our work explicates the innovative design of a nanohybrid photoanode playing a crucial role in the efficient electronic interactions in the space-charge layer between the photoanode and seawater-electrolyte interface for effective seawater splitting

Ultrastable, High Photoelectrocatalytic Performance of Altervalent Cation-Doped BiVO₄ Photoanode and Effect of Interfacial Contact with Nanoporous Carbon for Seawater Splitting Using a 3D-Printed Flow Device

Solar-driven direct seawater electrocatalysis is a promising technology for sustainable large-scale green-H2 fuel generation. In this work, we systematically investigate the influence of altervalent cation doping into the Bi3+ and V5+ sites of scheelite BiVO4 via a sustainable microwave-assisted hydrothermal (MW-HT) technique within a few minutes (12 min) at as low a temperature of 190 °C. We observed that lower-valent cation (Cs+, Ba2+, Co2+, and In3+) doping favors monoclinic-phase formation; however, higher-valent cations (Hf4+, Nb5+, and Mo6+) facilitated the thermodynamically unfavorable tetragonal-zircon type BiVO4. Interestingly, mixed phases of monoclinic-tetragonal BiVO4 have been obtained upon codoping of Co and Mo, exhibiting enhanced photocurrent density (Jp = 5.8 mA cm–2) among other doped BiVO4 samples. To increase the overall charge-transfer kinetics, we construct a nanoporous carbon with a Co and Mo codoped BiVO4 hybrid photoanode showing a remarkable (∼5-fold) enhancement in photoelectrochemical (PEC) freshwater splitting with the highest recorded photocurrent density of Jp = 6.9 mA cm–2 at 1.23 V vs RHE, AM1.5 G in 0.5 M Na2SO4 electrolyte solution, in comparison to pristine BiVO4 (1.45 mA cm–2) under simulated visible light. The superior performance is due to oxygen vacancy (OV)-related defect levels functioning as electron-trap sites promoting fast charge separation and surface adsorption for generating excess holes at the nanohybrid photoanode. In order to investigate how the nanohybrid photoanode affects the charge-carrier recombination rate and oxygen evolution reaction (OER) in seawater, we designed a compartmentalized three-dimensional (3D)-printed membrane-less, continuous-flow PEC device to produce massive H2 fuel. Significantly, we observed an enhanced Jp of 3.8 mA cm–2 accompanied by an outstanding long-term photostability of 4 h, achieved due to the rapid transfer of photostimulated holes from the nanohybrid photoanode to the electrolyte, promoted by the internal electric field over the constructed Mott–Schottky heterostructure. Thus, our work explicates the innovative design of a nanohybrid photoanode playing a crucial role in the efficient electronic interactions in the space-charge layer between the photoanode and seawater-electrolyte interface for effective seawater splitting

Ultrastable, High Photoelectrocatalytic Performance of Altervalent Cation-Doped BiVO₄ Photoanode and Effect of Interfacial Contact with Nanoporous Carbon for Seawater Splitting Using a 3D-Printed Flow Device

Solar-driven direct seawater electrocatalysis is a promising technology for sustainable large-scale green-H2 fuel generation. In this work, we systematically investigate the influence of altervalent cation doping into the Bi3+ and V5+ sites of scheelite BiVO4 via a sustainable microwave-assisted hydrothermal (MW-HT) technique within a few minutes (12 min) at as low a temperature of 190 °C. We observed that lower-valent cation (Cs+, Ba2+, Co2+, and In3+) doping favors monoclinic-phase formation; however, higher-valent cations (Hf4+, Nb5+, and Mo6+) facilitated the thermodynamically unfavorable tetragonal-zircon type BiVO4. Interestingly, mixed phases of monoclinic-tetragonal BiVO4 have been obtained upon codoping of Co and Mo, exhibiting enhanced photocurrent density (Jp = 5.8 mA cm–2) among other doped BiVO4 samples. To increase the overall charge-transfer kinetics, we construct a nanoporous carbon with a Co and Mo codoped BiVO4 hybrid photoanode showing a remarkable (∼5-fold) enhancement in photoelectrochemical (PEC) freshwater splitting with the highest recorded photocurrent density of Jp = 6.9 mA cm–2 at 1.23 V vs RHE, AM1.5 G in 0.5 M Na2SO4 electrolyte solution, in comparison to pristine BiVO4 (1.45 mA cm–2) under simulated visible light. The superior performance is due to oxygen vacancy (OV)-related defect levels functioning as electron-trap sites promoting fast charge separation and surface adsorption for generating excess holes at the nanohybrid photoanode. In order to investigate how the nanohybrid photoanode affects the charge-carrier recombination rate and oxygen evolution reaction (OER) in seawater, we designed a compartmentalized three-dimensional (3D)-printed membrane-less, continuous-flow PEC device to produce massive H2 fuel. Significantly, we observed an enhanced Jp of 3.8 mA cm–2 accompanied by an outstanding long-term photostability of 4 h, achieved due to the rapid transfer of photostimulated holes from the nanohybrid photoanode to the electrolyte, promoted by the internal electric field over the constructed Mott–Schottky heterostructure. Thus, our work explicates the innovative design of a nanohybrid photoanode playing a crucial role in the efficient electronic interactions in the space-charge layer between the photoanode and seawater-electrolyte interface for effective seawater splitting

Ultrastable, High Photoelectrocatalytic Performance of Altervalent Cation-Doped BiVO₄ Photoanode and Effect of Interfacial Contact with Nanoporous Carbon for Seawater Splitting Using a 3D-Printed Flow Device

Solar-driven direct seawater electrocatalysis is a promising technology for sustainable large-scale green-H2 fuel generation. In this work, we systematically investigate the influence of altervalent cation doping into the Bi3+ and V5+ sites of scheelite BiVO4 via a sustainable microwave-assisted hydrothermal (MW-HT) technique within a few minutes (12 min) at as low a temperature of 190 °C. We observed that lower-valent cation (Cs+, Ba2+, Co2+, and In3+) doping favors monoclinic-phase formation; however, higher-valent cations (Hf4+, Nb5+, and Mo6+) facilitated the thermodynamically unfavorable tetragonal-zircon type BiVO4. Interestingly, mixed phases of monoclinic-tetragonal BiVO4 have been obtained upon codoping of Co and Mo, exhibiting enhanced photocurrent density (Jp = 5.8 mA cm–2) among other doped BiVO4 samples. To increase the overall charge-transfer kinetics, we construct a nanoporous carbon with a Co and Mo codoped BiVO4 hybrid photoanode showing a remarkable (∼5-fold) enhancement in photoelectrochemical (PEC) freshwater splitting with the highest recorded photocurrent density of Jp = 6.9 mA cm–2 at 1.23 V vs RHE, AM1.5 G in 0.5 M Na2SO4 electrolyte solution, in comparison to pristine BiVO4 (1.45 mA cm–2) under simulated visible light. The superior performance is due to oxygen vacancy (OV)-related defect levels functioning as electron-trap sites promoting fast charge separation and surface adsorption for generating excess holes at the nanohybrid photoanode. In order to investigate how the nanohybrid photoanode affects the charge-carrier recombination rate and oxygen evolution reaction (OER) in seawater, we designed a compartmentalized three-dimensional (3D)-printed membrane-less, continuous-flow PEC device to produce massive H2 fuel. Significantly, we observed an enhanced Jp of 3.8 mA cm–2 accompanied by an outstanding long-term photostability of 4 h, achieved due to the rapid transfer of photostimulated holes from the nanohybrid photoanode to the electrolyte, promoted by the internal electric field over the constructed Mott–Schottky heterostructure. Thus, our work explicates the innovative design of a nanohybrid photoanode playing a crucial role in the efficient electronic interactions in the space-charge layer between the photoanode and seawater-electrolyte interface for effective seawater splitting

RNF43 and ZNRF3 are commonly altered in serrated pathway colorectal tumorigenesis

Serrated pathway colorectal cancers (CRCs) are characterised by a BRAF mutation and half display microsatellite instability (MSI). The Wnt pathway is commonly upregulated in conventional CRC through APC mutation. By contrast, serrated cancers do not mutate APC. We investigated mutation of the ubiquitin ligases RNF43 and ZNRF3 as alternate mechanism of altering the Wnt signal in serrated colorectal neoplasia. RNF43 was mutated in 47/54(87%) BRAF mutant/MSI and 8/33(24%) BRAF mutant/microsatellite stable cancers compared to only 3/79(4%) BRAF wildtype cancers (p < 0.0001). ZNRF3 was mutated in 16/54(30%) BRAF mutant/MSI and 5/33(15%) BRAF mutant/microsatellite stable compared to 0/27 BRAF wild type cancers (p=0.004). An RNF43 frameshift mutation (X659fs) occurred in 80% BRAF mutant/MSI cancers. This high rate was verified in a second series of 25/35(71%) BRAF mutant/MSI cancers. RNF43 and ZNRF3 had lower transcript expression in BRAF mutant compared to BRAF wildtype cancers and less cytoplasmic protein expression in BRAF mutant/MSI compared to other subtypes. Treatment with a porcupine inhibitor reduced RNF43/ZNRF3 mutant colony growth by 50% and synergised with a MEK inhibitor to dramatically reduce growth. This study suggests inactivation of RNF43 and ZNRF3 is important in serrated tumorigenesis and has identified a potential therapeutic strategy for this cancer subtype

Defining characteristics of genital health in South African adolescent girls and young women at high risk for HIV infection.

The genital tract of African women has been shown to differ from what is currently accepted as 'normal', defined by a pH≤4.5 and lactobacilli-dominated microbiota. Adolescent girls and young women (AGYW) from sub-Saharan Africa are at high risk for HIV, and we hypothesized that specific biological factors are likely to be influential. This study aimed to compare characteristics of vaginal health in HIV-negative AGYW (16-22-years-old), from two South African communities, to international norms. We measured plasma hormones, vaginal pH, presence of BV (Nugent scoring), sexually transmitted infections (multiplex PCR for Chlamydia trachomatis, Neisseria gonorrhoea, Trichomonas vaginalis, Mycoplasma genitalium) and candidiasis (Gram stain) in AGYW (n = 298) from Cape Town and Soweto. Cervicovaginal microbiota was determined by 16S pyrosequencing; 44 genital cytokines were measured by Luminex; and cervical T-cell activation/proliferation (CCR5, HLA-DR, CD38, Ki67) was measured by multiparametric flow cytometry. 90/298 (30.2%) AGYW were negative for BV, candidiasis and bacterial STIs. L. crispatus and L. iners were the dominant bacteria in cervicovaginal swabs, and the median vaginal pH was 4.7. AGYW with L. crispatus-dominant microbiota (42.4%) generally had the lowest cytokine concentrations compared to women with more diverse microbiota (34/44 significantly upregulated cytokines). Frequencies of CCR5+CD4+ T-cells co-expressing CD38 and HLA-DR correlated positively with interleukin (IL)-6, TNF-α, GRO-α, macrophage inflammatory protein (MIP)-1α, and IL-9. While endogenous oestrogen had an immune-dampening effect on IL-6, TNF-related apoptosis-inducing ligand (TRAIL) and IL-16, injectable hormone contraceptives (DMPA and Net-EN) were associated with significantly lower endogenous hormone concentrations (p<0.0001 for oestrogen and progesterone) and upregulation of 34/44 cytokines. Since genital inflammation and the presence of activated CD4+ T cells in the genital tract have been implicated in increased HIV risk in South African women, the observed high levels of genital cellular activation and cytokines from AGYW may point towards biological factors increasing HIV risk in this region