With the past decade of worldwide sustained efforts on artificial photosynthesis for photocatalytic solar water splitting and clean hydrogen generation by dedicated researchers and engineers from different disciplines, substantial progress has been achieved in raising its overall efficiency along with finding new photocatalysts. Various materials, systems, devices, and better fundamental understandings of the interplay between interfacial chemistry, electronic structure, and photogenerated charge dynamics involved have been developed. Nevertheless, the overall photocatalytic performance is yet to achieve its maximum theoretical limit. Moreover, the stability of well-known semiconductors (as well as novel ones) remains the biggest challenge that scientists are facing to develop durable industrial-scale devices for large-scale water oxidation and overall solar water splitting. In this Perspective, we summarize the major achievements and the different approaches carried out to improve the stability and performance of photoelectrodes based on sulfide, nitride, and phosphide semiconductors.

No abstract

A unique BiVO4/reduced graphene oxide (rGO)/NiFe hydroxide photoanode with oriented hierarchical nanostructure was fabricated via a facile and scalable solution route. Microstructure analysis shows that the ternary nanocomposite system presented a nanopyramid configuration with BiVO4 nanoarrays coated by sheetlike graphene interlayer and amorphous NiFe hydroxides. A maximum photocurrent density of 1.30 mA/cm2 at scan rate of 20 mV/s at 1.23 V vs reversible hydrogen electrode was obtained for the BiVO4/rGO/NiFe photoelectrode, which was almost three times as high as that of pristine BiVO4. A boost of photocurrent density was achieved as a result of the synergistic effects between graphene “shuttle” interlayer and NiFe-based nanoarrays cocatalyst outer layer. Herein, rGO acts as an intermediate layer facilitating transfer of the photogenerated charge carriers, improving the adhesion of NiFe nanoarrays cocatalyst layer on the substrate and enhancing the stability and photoelectrochemical response of photoanode. This work demonstrates that tunable multicomponent design and rational hierarchical structure control are efficient approaches to enhance the photoelectrochemical water splitting performance of photoelectrode.

Supplementary Figure 1│ Crystal structure parameters of optimized unit cell and atomic positions of ms-BiVO 4 bulk for the DFT calculations in this work. Supplementary Figure 2│ BiVO 4 unit cell. Wave-function electron density distributions for the bands (at G-point) which contribute to highlighted DOS features.

A metal-free flexible protonated g-C 3 N 4 /carbon dots (pCN/C dots) photoanode has been fabricated on polyethylene terephtalate (PET) /indium tin oxide (ITO) substrate by a facile room temperature electrophoretic approach. The pCN/C dots photoanode gives an increased anodic photocurrent of 38 mA/cm 2 at 1 V vs. RHE under illumination with simulated one sun conditions, which is about 3 times higher than that of the pristine pCN. The improved photoresponse of the pCN/C dots film was found as a result from enhanced light absorption and decreased charge transfer resistance with the incorporation of C dots. The successful deposition of pCN/C dots on flexible conductive PET substrate holds promising application in multiple electronic and photoelectronic devices.Artificial photosynthesis enables the generation of large-scale, clean and sustainable energy through solar water splitting and other chemical fuel syntheses. Photoelectrochemical (PEC) water splitting is regarded as one of the most promising artificial photosynthesis approaches for solar fuel production. [1,2] Due to their superior properties of transparency and conductivity, transparent conductive oxide (TCO) layers (such as In 2 O 3 , ZnO or SnO 2 films) deposited on glass are widely used as substrates for PEC and photovoltaic devices. [3][4][5] However, the expensive, fragile and inflexible glass-TCO substrate nature has inhibited the development of large scale roll-to-roll solar cell. One alternative approach is the taking polymer foils as substrate physical supporter substrates instead of glass. PET coated with an ITO-layer possess mechanical flexibility, optical clarity, light weight, and low fabrication cost, which is highly desirable in large-area production as well as the ultimate goal of solar hydrogen production industrialization.It is wide interest in the search for robust and metal-free visible-light-driven photocatalysts, which are of great economic compatible for practical use. Graphitic carbon nitride (g-CN) has attracted great attention due to its moderate band gap of 2.7 eV, good chemical stability under light irradiation, low cost, and non-toxicity. It has been considered as a good photocatalyst for solar fuel conversion and pollutant degradation. [6] However, there are limited reports on its PEC properties as its PEC application research has been hindered by the significant challenge of depositing a uniform CN films on substrates. Several methods have been developed to prepare CN films, such as spin-coating, [7] drop-casting [8] or thermal vapor condensation. [9,10] All these methods of depositing the CN powders on substrates shows low photocurrent (several mA/cm 2 ) or need high temperature. Unlike glass-based photoelectrode, the plastic-based photoelectrode need low-temperature sintering technique below 150 8C due to the decomposition of the plastic at high temperature, so in this work, a room temperature electrophoretic method has been employed to deposit g-CN onto PET substrate. For the first step, we prepared protonated g-CN (pCN) by t...