Recent developments in cadmium sulphide-based photocatalysts including heterojunctions, solid solutions and quantum dots for photocatalytic H₂ production are reviewed.

Solar H₂ generation from water has been intensively investigated as a clean method to convert solar energy into hydrogen fuel. During the past few decades, many studies have demonstrated that metal complexes can act as efficient photoactive materials for photocatalytic H₂ production. Here, we review the recent progress in the application of metal-complex chromophores to solar-to-H₂ conversion, including metal-complex photosensitizers and supramolecular photocatalysts. A brief overview of the fundamental principles of photocatalytic H₂ production is given. Then, different metal-complex photosensitizers and supramolecular photocatalysts are introduced in detail, and the most important factors that strictly determine their photocatalytic performance are also discussed. Finally, we illustrate some challenges and opportunities for future research in this promising area.

Impurity doping is an effective approach to tuning the optoelectronic performance of host materials by imparting extrinsic electronic channels. Herein, a family of lanthanide (Ln³⁺) ions was successfully incorporated into a Bi:Cs₂AgInCl₆ lead-free double-perovskite (DP) semiconductor, expanding the spectral range from visible (Vis) to near-infrared (NIR) and improving the photoluminescence quantum yield (PLQY). After multidoping with Nd, Yb, Er and Tm, Bi/Ln:Cs₂AgInCl₆ yielded an ultrabroadband continuous emission spectrum with a full width at half-maximum of ~365 nm originating from intrinsic self-trapped exciton recombination and abundant 4f–4f transitions of the Ln³⁺ dopants. Steady-state and transient-state spectra were used to ascertain the energy transfer and emissive processes. To avoid adverse energy interactions between the various Ln³⁺ ions in a single DP host, a heterogeneous architecture was designed to spatially confine different Ln³⁺ dopants via a “DP-in-glass composite” (DiG) structure. This bottom-up strategy endowed the prepared Ln³⁺-doped DIG with a high PLQY of 40% (nearly three times as high as that of the multidoped DP) and superior long-term stability. Finally, a compact Vis–NIR ultrabroadband (400~2000 nm) light source was easily fabricated by coupling the DiG with a commercial UV LED chip, and this light source has promising applications in nondestructive spectroscopic analyses and multifunctional lighting.

Traditional optical temperature sensors based on the rare earth fluorescence intensity ratio of two thermally coupled energy states have intrinsic limitations such as low relative sensitivity and large detection error due to the requirement of a narrow energy gap. Herein, a strategy involving the use of rare earth and transition metal dual-emitting centers with completely different thermal-quenching behaviors has been developed to achieve high temperature sensitivity and good discrimination of signals. In particular, Eu³⁺/Mn⁴⁺:Y₃Al₅O₁₂ with strikingly high absolute and relative sensitivities of 0.441 K⁻¹ and 4.81% K⁻¹ as well as a large energy gap of 2100 cm⁻¹ was realized by taking advantage of Eu³⁺ luminescence as a reference signal and Mn⁴⁺ luminescence as a temperature signal. The versatility of the proposed strategy has been demonstrated by adopting other Tb³⁺/Mn⁴⁺, Dy³⁺/Mn⁴⁺, Eu³⁺/Cr³⁺ and Dy³⁺/Cr³⁺ dual-activator combinations. It is expected that this preliminary study will provide an important advance in exploring novel self-referencing optical thermometry with excellent performance.