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Silver bismuth iodides are non-toxic and comparatively cheap photovoltaic materials, but their wide bandgaps and downshifted valence band edges limit their This article is protected by copyright. All rights reserved. performance as light absorbers in solar cells. Herein, we introduce a strategy to tune the optoelectronic properties of silver bismuth iodides by partial anionic substitution with the sulfide dianion. A consistent narrowing of the bandgap by 0.1 eV and an upshift of the valence band edge by 0.1-0.3 eV upon modification with sulfide are demonstrated for AgBiI 4 , Ag 2 BiI 5 , Ag 3 BiI 6 and AgBi 2 I 7 compositions. Solar cells based on silver bismuth sulfoiodides embedded into a mesoporous TiO 2 electron transporting scaffold, and a poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] hole transporting layer significantly outperform devices based on sulfide-free materials, mainly due to enhancements in the photocurrent by up to 48 %. A power conversion efficiency of 5.44 ± 0.07 % (J sc = 14.6 ± 0.1 mA cm -2 ; V oc = 569 ± 3 mV; fill factor = 65.7 ± 0.3 %) under 1 sun irradiation and stability under ambient conditions for over a month are demonstrated. The results reported herein indicate that further improvements should be possible with this new class of photovoltaic materials upon advances in the synthesis procedures and an increase in the level of sulfide anionic substitution.

The carbon 1s photoelectron spectrum is the most widely fit and analyzed narrow scan in the x-ray photoelectron spectroscopy (XPS) literature. It is, therefore, critically important to adopt well-established protocols based on best practices for its analysis, since results of these efforts affect research outcomes in a wide range of different application areas across materials science. Unfortunately, much XPS peak fitting in the scientific literature is inaccurate. In this guide, we describe and explain the most common problems associated with C 1s narrow scan analysis in the XPS literature. We then provide an overview of rules, principles, and considerations that, taken together, should guide the approach to the analysis of C 1s spectra. We propose that following this approach should result in (1) the avoidance of common problems and (2) the extraction of reliable, reproducible, and meaningful information from experimental data.

The synthesis of hydrogen peroxide (H2O2) from H2O and O2 by metal-free photocatalysts (e.g., graphitic carbon nitride, C3N4) is a potentially promising approach to generate H2O2. However, the photocatalytic H2O2 generation activity of the pristine C3N4 in pure H2O is poor due to unpropitious rapid charge recombination and unfavorable selectivity. Herein, we report a facile method to boost the photocatalytic H2O2 production by grafting cationic polyethylenimine (PEI) molecules onto C3N4. Experimental results and density functional theory (DFT) calculations demonstrate PEI can tune the local electronic environment of C3N4. The unique intermolecular electronic interaction in PEI/C3N4 not only improves the electron–hole separation but also promotes the two-electron O2 reduction to H2O2 via the sequential two-step single-electron reduction route. With the synergy of improved charge separation and high selectivity of two-electron O2 reduction, PEI/C3N4 exhibits an unexpectedly high H2O2 generation activity of 208.1 μmol g–1 h–1, which is 25-fold higher than that of pristine C3N4. This study establishes a paradigm of tuning the electronic property of C3N4 via functional molecules for boosted photocatalysis activity and selectivity.

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