Integrating Perovskite Photovoltaics and Noble-Metal-Free Catalysts toward Efficient Solar Energy Conversion and H2S Splitting

Hydrogen sulfide (H2S) has been considered as a potential hydrogen source. Identifying efficient solar-driven processes and low-cost materials that can extract hydrogen from H2S is highly attractive. Herein, for the first time, we reported the establishment of a perovskite photovoltaic-electrolysis (PV-EC) H2S splitting system by integrating a single perovskite solar cell, noble-metal-free catalysts, and H2S splitting reaction with the aid of mediators. The as-established system delivered a solar-to-chemical energy conversion efficiency of up to 13.5% during the PV-EC step by using molybdenum-tungsten phosphide (Mo-W-P) as the catalyst for a hydrogen evolution reaction (HER) and a graphite carbon sheet as the catalyst for the oxidation of mediators, respectively. To the best of our knowledge, this is among the highest value ever reported for the artificial conversion of solar to chemical energy using perovskite solar cells. Moreover, upon integration with the PV-EC system, a H2S splitting reaction with a net energy conversion efficiency of 3.5% can be accomplished, and the overall energy consumption to obtain an equivalent amount of H-2 from H2S is reduced by ca. 43.3% compared with that from water splitting. This paradigm of producing value-added chemicals by consuming negative value waste products is solely based on low-cost materials and a simpler system configuration, which significantly improves the economic sustainability of the process

Moisture-assisted preparation of compact GaN:ZnO photoanode toward efficient photoelectrochemical water oxidation

Developing strategies that can promote charge transportation in photodevices is crucial for achieving high solar energy conversion efficiency. Herein a moisture-assisted nitridation approach is presented for the fabrication of efficient gallium-zinc oxynitride (GaN:ZnO) photoanode with compact structure to facilitate the charge transportation. With moisture-assisted nitridation, the charge separation efficiency and injection efficiency obtained on GaN:ZnO photoanode are significantly enhanced. Correspondingly, the photocurrent at 1.23 V vs reversible hydrogen electrode (RHE) has 18 folds improvement compared with that prepared without moisture assistance. Furthermore, via treating with HCl acid and modification with cobalt phosphate (CoPi) as a cocatalyst, state-of-the-art photocurrent over 2.0 mA cm(-2) is achieved on independent GaN:ZnO photoanode when bias is higher than 1.4 V vs RHE. To the best of our knowledge, this is the first paradigm of moisture-assisted preparing oxynitride-based photoanode. The participation of moisture is found to improve the interconnection between adjacent GaN:ZnO nanoparticles as well as that between the GaN:ZnO film and the underlying substrate. Moreover, the volatilization of Zn can be substantially suppressed due to the modulation of reaction pathway by moisture. These two factors are confirmed to be the main reasons for the enhanced charge transportation and PEC performance obtained on GaN:ZnO photoanode

Photocatalytic Water Oxidation on BiVO4 with the Electrocatalyst as an Oxidation Cocatalyst: Essential Relations between Electrocatalyst and Photocatalyst

The oxygen evolution is kinetically the key step in the photocatalytic water splitting. Cocatalysts could lower the activation potential for O-2 evolution. However, the cocatalyst for O-2 evolution has been less investigated, and few effective cocatalysts were reported. This paper reports that the O-2 evolution rate of photocatalytic water splitting under visible light irradiation can be significantly enhanced when the electrocatalyst cobalt phosphate (denoted as CoPi) was deposited on BiVO4. The photocurrent density is also greatly enhanced by loading CoPi on BiVO4 electrode, and this enhancement in performance shows the similar trend between the photocatalytic activity and photocurrent density. We also found that this tendency is true for BiVO4 loaded with a series of different electrocatalysts as the cocatalysts. These results demonstrate that an effective electrocatalyst of water oxidation can be also an effective cocatalyst for O-2 evolution from photocatalytic water oxidation. By depositing the CoPi as the oxidation cocatalyst and Pt as the reduction cocatalyst on an yttrium-doped BiVO4 (Bi0.5Y0.5VO4), overall water splitting reaction to H-2 and O-2 was realized. Our work also reveals the essential relations between photocatalysis and electrocatalysis in water splitting reaction

Fabrication of a robust tantalum nitride photoanode from a flame-heating-derived compact oxide film

Photoelectrochemical (PEC) water splitting provides an attractive way of converting solar energy into hydrogen energy. To make this approach practical, it is crucial to develop strategies that can be used to fabricate efficient photoelectrodes in a scalable manner. Herein, we report a rapid flame heating method to prepare a Ta2O5 precursor film for a Ta3N5 photoanode. By varying the parameters of flame heating, rational control over the physicochemical nature of the Ta2O5 precursor film can be realized. With the following nitridation treatment, the compact precursor film can be transformed into a tight-knit Ta3N5-based nitride film which strongly stuck to the underlying conductive Ta substrate. As a result of the close interfacial connections and reasonable conductivity achieved through the manipulation of the duration of flame heating, an enhanced charge-separation efficiency was obtained for the as-prepared Ta3N5 photoanode. Furthermore, with the help of a ferrihydrite layer, the photocurrent density for PEC water oxidation on the optimum Ta3N5 photoanode reached circa 3.53mAcm(-2) at 1.23V vs. RHE, which is among the best values reported for planar Ta3N5-based photoanodes. This report highlights the advantages of flame heating over traditional heating methods for preparing precursor films for further processing or functionalization

Does MRI-detected cranial nerve involvement affect the prognosis of locally advanced nasopharyngeal carcinoma treated with intensity modulated radiotherapy?

Nasopharyngeal carcinoma (NPC) is one of the common cancers in South China. It can easily invade into cranial nerves, especially in patients with local advanced disease. Despite the fact that the magnetic resonance imaging (MRI) findings are not always consistent with the symptoms of CN palsy, MRI is recommended for the detection of CN involvement (CNI). However, the prognostic impact of MRI-detected CNI in NPC patients is still controversial. To investigate the prognostic value of MRI detected CNI, we performed a retrospective analysis on the clinical data of 375 patients with NPC who were initially diagnosed by MRI. All patients had T3-4 disease and received radical intensity modulated radiation therapy (IMRT) as their primary treatment. The incidence of MRI-detected CNI was 60.8%. A higher incidence of MRI-detected CNI was observed in T4 disease compared with T3 disease (96.8% vs. 42.8%, P<0.001), and a higher incidence was also found in patients with Stage IV disease compared with those with Stage III disease (91.5% vs. 42.3%; P<0.001). The local relapse-free survival (LRFS), distant metastasis-free survival (DMFS), and overall survival (OS) of patients with T3 disease, with or without MRI-detected CNI, was superior to that of patients with T4 disease (P<0.05). No significant differences in LRFS, DMFS or OS were observed between T3 patients with or without MRI-detected CNI. The survival of Stage III patients with or without MRI-detected CNI was significantly superior to that of Stage IV patients (P<0.01), but there was no significant difference between Stage III patients with or without MRI-detected CNI for all endpoints. Therefore, when treated with IMRT, MRI-detected CNI in patients with NPC does not appear to affect the prognosis. In patients with clinical T3 disease, the presence of MRI-detected CNI is not sufficient evidence for defining T4 disease

Risk-adapted locoregional radiotherapy strategies based on a prognostic nomogram for de novo metastatic nasopharyngeal carcinoma patients treated with chemoimmunotherapy

Abstract To develop a prognostic nomogram for individualized strategies on locoregional radiation therapy (LRRT) in patients with de novo metastatic nasopharyngeal carcinoma (dmNPC) treated with chemoimmunotherapy. Ninety patients with dmNPC treated with chemoimmunotherapy and diagnosed between 2019 and 2022 were included in our study. Cox regression analysis was performed to identify independent prognostic factors for overall survival (OS) and progression-free survival (PFS) to establish a nomogram. With a median follow-up of 17.5 months, the median PFS and OS were 24.9 months and 29.4 months, respectively. Sixty-nine patients and twenty-one patients were included in the LRRT group and without LRRT group, respectively. Multivariate analysis revealed that younger age, lower EBV DNA copy number before treatment, a single metastatic site, more cycles of chemotherapy and immunotherapy were significantly associated with better OS. A prognostic nomogram was constructed incorporating the above 5 independent factors, with a C-index of 0.894. Patients were divided into low- and high-risk cohorts based on nomogram scores. A significant improvement in OS was revealed in the LRRT group compared with the without-LRRT group for patients in the high-risk cohort (HR = 2.46, 95% CI 1.01–6.00, P = 0.049), while the OS was comparable between the two groups in the low-risk cohort. Our study indicates that LRRT may be associated with better prognosis in high-risk patients with dmNPC in the era of immunotherapy

NF-κB Signaling Regulates Epstein–Barr Virus BamHI-Q-Driven EBNA1 Expression

Epstein–Barr virus (EBV) nuclear antigen 1 (EBNA1) is one of the few viral proteins expressed by EBV in nasopharyngeal carcinoma (NPC), most likely because of its essential role in maintaining the viral genome in EBV-infected cells. In NPC, EBNA1 expression is driven by the BamHI-Q promoter (Qp), which is regulated by both cellular and viral factors. We previously determined that the expression of another group of EBV transcripts, BamHI-A rightward transcripts (BARTs), is associated with constitutively activated nuclear factor-κB (NF-κB) signaling in NPC cells. Here, we show that, like the EBV BART promoter, the EBV Qp also responds to NF-κB signaling. NF-κB p65, but not p50, can activate Qp in vitro, and NF-κB signaling regulates Qp-EBNA1 expression in NPC cells, as well as in other EBV-infected epithelial cells. The introduction of mutations in the putative NF-κB site reduced Qp activation by the NF-κB p65 subunit. Binding of p65 to Qp was shown by chromatin immunoprecipitation (ChIP) analysis, while electrophoretic mobility shift assays (EMSAs) demonstrated that p50 can also bind to Qp. Inhibition of NF-κB signaling by the IκB kinase inhibitor PS-1145 resulted in the downregulation of Qp-EBNA1 expression in C666-1 NPC cells. Since EBNA1 has been reported to block p65 activation by inhibiting IKKα/β through an unknown mechanism, we suggest that, in NPC, NF-κB signaling and EBNA1 may form a regulatory loop which supports EBV latent gene expression, while also limiting NF-κB activity. These findings emphasize the role of NF-κB signaling in the regulation of EBV latency in EBV-associated tumors

Photocatalytic Water Oxidation on BiVO₄ with the Electrocatalyst as an Oxidation Cocatalyst: Essential Relations between Electrocatalyst and Photocatalyst

The oxygen evolution is kinetically the key step in the photocatalytic water splitting. Cocatalysts could lower the activation potential for O₂ evolution. However, the cocatalyst for O₂ evolution has been less investigated, and few effective cocatalysts were reported. This paper reports that the O₂ evolution rate of photocatalytic water splitting under visible light irradiation can be significantly enhanced when the electrocatalyst cobalt–phosphate (denoted as CoPi) was deposited on BiVO₄. The photocurrent density is also greatly enhanced by loading CoPi on BiVO₄ electrode, and this enhancement in performance shows the similar trend between the photocatalytic activity and photocurrent density. We also found that this tendency is true for BiVO₄ loaded with a series of different electrocatalysts as the cocatalysts. These results demonstrate that an effective electrocatalyst of water oxidation can be also an effective cocatalyst for O₂ evolution from photocatalytic water oxidation. By depositing the CoPi as the oxidation cocatalyst and Pt as the reduction cocatalyst on an yttrium-doped BiVO₄ (Bi_0.5Y_0.5VO₄), overall water splitting reaction to H₂ and O₂ was realized. Our work also reveals the essential relations between photocatalysis and electrocatalysis in water splitting reaction

Integrating Perovskite Photovoltaics and Noble-Metal-Free Catalysts toward Efficient Solar Energy Conversion and H₂S Splitting

Hydrogen sulfide (H₂S) has been considered as a potential hydrogen source. Identifying efficient solar-driven processes and low-cost materials that can extract hydrogen from H₂S is highly attractive. Herein, for the first time, we reported the establishment of a perovskite photovoltaic-electrolysis (PV-EC) H₂S splitting system by integrating a single perovskite solar cell, noble-metal-free catalysts, and H₂S splitting reaction with the aid of mediators. The as-established system delivered a solar-to-chemical energy conversion efficiency of up to 13.5% during the PV-EC step by using molybdenum–tungsten phosphide (Mo–W–P) as the catalyst for a hydrogen evolution reaction (HER) and a graphite carbon sheet as the catalyst for the oxidation of mediators, respectively. To the best of our knowledge, this is among the highest value ever reported for the artificial conversion of solar to chemical energy using perovskite solar cells. Moreover, upon integration with the PV-EC system, a H₂S splitting reaction with a net energy conversion efficiency of 3.5% can be accomplished, and the overall energy consumption to obtain an equivalent amount of H₂ from H₂S is reduced by ca. 43.3% compared with that from water splitting. This paradigm of producing value-added chemicals by consuming negative value waste products is solely based on low-cost materials and a simpler system configuration, which significantly improves the economic sustainability of the process